Publications by and About J.C. Kapteyn, His Honors and Academic Genealogy

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Appendix A Publications by and About J.C. Kapteyn, His Honors and Academic Genealogy

The compulsion to write should be distrusted, unlike the urge to formulate. Godfried Bomans (1913–1971).1

A.1 Publications by J.C. Kapteyn

Below I present a list of all known publications by Jacobus Cornelius Kapteyn. As director he must have been involved in supervising all activities, and therefore I have included all papers in the Publications of the Astronomical Laboratory at Gro- ningen during Kapteyn’s lifetime, with the exception of Willem de Sitter’s papers on the Galilean satellites of Jupiter. I have also included papers that are directly related to projects Kapteyn was involved in personally, such as those based on PhD theses written under his supervision. PhD theses that have not been published sep- arately in astronomical periodicals or observatory annals, etc., are included in the list as well. Many, but far from all, of these publications have been listed by the NASA Astronomy Data System ADS [1] and usually scanned copies are available there. I have indicated the ADS code at the end of the full reference between square brackets. The publications by the Royal Netherlands Academy of Arts and Sciences (KNAW) are made available on the Digital Library – Dutch History of science web centre [2]. The papers Kapteyn (1883) and Kapteyn (1884) are available electronically by downloading a pdf-ﬁle of the full volume 3 of Copernicus [3]. The table of contents at the end of that ﬁle lists the papers with their dates of publication; for these papers the dates are Febr. 28, 1883, and Febr. 12, 1884.

1De dwang om te schrijven moet men wantrouwen, de drang om te formuleren niet. Godfried Bomans was a Dutch writer and television personality.

© Springer International Publishing Switzerland 2015 611 P.C. van der Kruit, Jacobus Cornelius Kapteyn, Astrophysics and Space Science Library 416, DOI 10.1007/978-3-319-10876-6 612 A Publications, Honors and Academic Genealogy

Fig. A.1 The books of Kapteyn in the Kapteyn Room. From the left the three volumes of the Cape Photographic Durchmusterung plus two of the revisions, four bound volumes with Kapteyn’s publications (see Fig. A.2) and one with his Mount Wilson publications up to 1920, Groningen Publications 1 through 37, the three Selected Areas (Systematic Plan) publications with Edward Pickering in the Harvard Annals and the Durchmusterung of the Special Plan (published in 1952). On the extreme right Kapteyn’s copy of Popular Astronomy by Simon Newcomb (Kapteyn Astro- nomical Institute)

On my Kapteyn Web-page [4], I provide the list in this Appendix, together with links to electronic copies of every publication. In Figs. A.1 to A.4 I show some pictures of Kapteyn’s books. For explanations see the captions.

Kapteyn. J. C. 1875. Onderzoek der trillende, platte vliezen [Study of vibrating ﬂat membranes], Ph.D. thesis defended at University of Utrecht on June 24, 1875. van de Sande Bakhuyzen, E. F. & Kapteyn, J. C. 1877a. Elemente und Ephemeride des Cometen b. 1877. Astronomische Nachrichten, 89, 251–252. [1877AN.....89..251 V] van de Sande Bakhuyzen, E. F. & Kapteyn, J. C. 1877b. Ephemeris of comet b. 1877 (Winnecke’s). The Observatory 1, 64–64. [1877Obs.....1...64V] van de Sande Bakhuyzen, H. G. & Kapteyn, J. C. 1879a. Beobachtungen der Heliometer-Sterne in Perseus. Astronomische Nachrichten, 95, 5–14. [1879AN.....95 ....5V] van de Sande Bakhuyzen, H. G. & Kapteyn, J. C. 1879b. Beobachtungen von Gill’s Mars-Sternen. Astronomische Nachrichten, 95, 33–42. [1879AN.....95...33V] Kapteyn, J. C. 1883. Uber¨ das Kepler’sche Problem. Copernicus 3, 25–34. Kapteyn, J. C. 1884. Uber¨ eine Methode die Polhohe¨ moglichtst¨ frei von System- atischen Fehlern zu bestimmen. Copernicus 3, 147–182. Kapteyn, J. C. & Kapteyn, W. 1884. Les sinus de quatrieme` ordre. Verhandelin- gen der Koninklijke Akademie van Wetenschappen, vier en twintigste deel, 1–98. Kapteyn, J. C. & Kapteyn, W. 1886. Die hoheren¨ sinus. XCIII. Bande der Sitzberichten der Kaiserlichen Akademie der Wissenshaften (Wien). II. Abteilung, April-Heft, Jahrgang 1886, 807–868. A.1 Publications by J.C. Kapteyn 613

Kapteyn, J. C. 1888a. Exposedelam´ ethode´ parallactique de mesure. Reduction´ des cliches´ . Bulletin de Comite´ International Permanent de la Carte du Ciel, I, 94–114. Kapteyn, J. C. 1888b. Addition au la methode´ parallactique de mesure. Bulletin de Comite´ International Permanent de la Carte du Ciel, I, 125–127. Kapteyn, J. C. 1888c. Bericht uber¨ die zur Herstellung einer Durchmusterung des sudlichen¨ Himmels ausgefuhrten¨ Arbeiten. Vierteljahrsschrift der Astronomi- sche Gesellsschaft, 23, 213–220. Kapteyn, J. C. 1889a. Vorlaufige¨ Mittheilung betr. Bestimmung von Fixstern- Parallaxen. Astronomische Nachrichten 123, 105. [1890AN....123..105K] Kapteyn, J. C. 1889b. Note relative de memoire´ de M. Bakhuyzen sur la mesure de cliches´ . Bulletin de Comite´ International Permanent de la Carte du Ciel, 242–250. Gill, D. & Kapteyn, J. C. 1889b. Expose´ d’un projet de M. J.-C. Kapteyn relative aladetermination´ des mouvements propres et des parallaxes d’etoiles´ . Bulletin de Comite´ International Permanent de la Carte du Ciel, 262–264. Kapteyn, J. C. 1890a. Uber¨ eine photographische Methode der Breitenbestim- mung aus Zenithsternen. Astronomische Nachrichten 125, 81–86. [1890AN....125... 81K] Kapteyn, J. C. 1890b. Sudliche¨ muthmasslich veranderliche¨ Sterne. Astronomi- sche Nachrichten 125, 165–170. [1890AN....125..165K] Kapteyn, J. C. 1890c. De bepaling van de parallaxis van vaste sterren door middel van registreerwaarnemingen. Verslagen en Mededelingen der Koninklijke Akademie van Wetenschappen, Afdeeling Natuurkunde, derde deel, 114–115. Kapteyn, J. C. 1890d. Zweiter Bericht uber¨ die zur Herstellung einer Durch- musterung des sudlichen¨ Himmels ausgefuhrten¨ Arbeiten. Vierteljahrsschrift der Astronomsiche Gesellsschaft, 25, 240–243. van de Sande Bakhuyzen, H. G., Kapteyn, J. C., et al. 1890a. Zonen-beobachtungen zwischen 29◦50 und 35◦10 Declination. Annalen van de Sterrewacht te Leiden, 5, I-LII,1–352. [1890AnLei...5....1.] van de Sande Bakhuyzen, H. G., Kapteyn, J. C., et al. 1890b. Reductionen der Zenitdistanzen der Fundsmentalsternen etc.. Annalen van de Sterrewacht te Leiden, 6, I-CXXIX,1–412. [1890AnLei...6....1.] Kapteyn, J. C. 1891a. Bestimmung von Parallaxen durch Registrir-Beobachtungen am Meridiankreise. Annalen van de Sterrewacht te Leiden 7, 117–244. [1897An Lei...7..117K] Boss, L. & Kapteyn, J. C. 1891. Bestimmung von Parallaxen durch Registrir- Beobachtungen am Meridian Kreise. Publications of the Astronomical Society of the Pacific 3, 346–353. [1891PASP....3..346K] Plummer, W. E. & Kapteyn, J. C. 1891. Stellar parallax, as determined by a transit instrument. The Observatory, 14, 259–263. [1891Obs....14..259P] Kapteyn, J. C. 1891b. De beteekenis der photographie voor de studie van de hoogere delen des hemels, address at the occasion of the transfer of office of Rector Magnificus at the University of Groningen on 15 September 1891. J.B. Wolters, Groningen. 614 A Publications, Honors and Academic Genealogy

Fig. A.2 The books of Kapteyn in the Kapteyn Room. Here we see three volumes with reprints of his own papers and one (red) with publications on the Star Streams. After binding all reprints together he had the pages renumbered sequentially. This looks like a streak of vanity in Kapteyn, but may be no more than a appreciation of order and neatness (Kapteyn Astronomical Institute)

Kapteyn, J. C. 1891c Verslag van de lotgevallen der Rijks-Universiteit te Gro- ningen in het studiejaar 1890–91, gegeven den 15den September 1891, door den aftredenden Rector-Magniﬁcus Dr J. C. Kapteyn. 1891. J.B. Wolters, Groningen. Kapteyn, J. C. 1892a. Plan et details´ de l’appareil parallactique de mesures. Bulletin de Comite´ International Permanent de la Carte du Ciel, I, 377–381. Kapteyn, J. C. 1892b. Theorie´ des erreurs de l’appareil parallactique de mesures et reduction´ de cliches´ . Bulletin de Comite´ International Permanent de la Carte du Ciel, I, 401–452 Kapteyn, J. C. 1892c. Difference systematique´ entre les grandeurs photographiques et visuelles dans le differentes region du ciel. Bulletin de Comite´ International Permanent de la Carte du Ciel, II, 131–158. Kapteyn, J. C. 1892d. Systematische verschillen tusschen de visueele en photographische helderheid der sterren in verschillende deelen der hemel. Verslagen en Mededelingen der Koninklijke Akademie van Wetenschappen, Afdeeling Natu- urkunde, negende deel, 393–394. Kapteyn, J. C. 1892e. De verdeeling an de sterren in de ruimte. Verslagen en Mededelingen der Koninklijke Akademie van Wetenschappen, Afdeeling Natu- urkunde, negende deel, 418–421. Kapteyn, J. C. 1892f. To what stellar system does our Sun belong? (Abstract). Publications of the Astronomical Society of the Paciﬁc 4, 259–260. [1892PASP....4.. 259K] A.1 Publications by J.C. Kapteyn 615

Kapteyn, J. C. 1892g. Dritter Bericht uber¨ die zur Herstellung einer Durchmus- terung des sudlichen¨ Himmels ausgefuhrten¨ Arbeiten. Vierteljahrsschrift der Astro- nomische Gesellsschaft, 27, 218–219. Kapteyn, J. C. 1893a. Over de verdeeling van de sterren in de ruimte. Koninklijke Akademie van Wetenschappen, Zittingsverslag 28 Januari 1893, 125–140. Kapteyn, J. C. 1893b. Measuring stellar photographs. Engineering Jan.27, 1893, 91–92 Kapteyn, J. C. 1893c. Uber¨ den neuen Fleming’schen Stern im Sternbilde Norma. Astronomische Nachrichten 134, 59. [1893AN....134...59K] Kapteyn, J. C. 1893d. Eene nieuwe methode ter bepaling van den afstand van vaste sterren. Handelingen van het vierde Nederlandsch Natuur- en Geneeskundig Congres, gehouden te Groningen op den 7den en 8sten April 1893, 70–75. Kapteyn, J. C. 1895. Over de verdeeling der kosmische snelheden. Koninklijke Akademie van Wetenschappen, Zittingsverslag 25 Mei 1895, 1–15. Kapteyn, J. C. 1896a. Corrections de refraction et d’aberration pour les coordonnees´ rectangulaires mesurees´ sur les cliches´ photographiques. Bulletin de Comite´ International Permanent de la Carte du Ciel, III, 17–44. Gill, D. & Kapteyn, J. C. 1896. The Cape Photographic Durchmusterung for the equinox 1875. Part I. Zones −18◦ to −37◦. Annals of the Cape Observatory, South Africa, 3, 1–845. [1896AnCap...3....1G] Kapteyn. J. C. 1896b. Openbare les gehouden bij de gelegenheid van de opening van het Sterrenkundig Laboratorium te Groningen. Hoitsema Brothers, Groningen. Kapteyn, J. C. 1896c. New southern variable stars. Astronomische Nachrichten 142, 75–78. [1896AN....142...75K] Kapteyn, J. C. 1897a. Verdeeling der kosmische snelheden. Toevoegsel aan de mededeeling van 5 Mei 1895. Koninklijke Akademie van Wetenschappen, Zit- tingsverslag 29 Mei 1897, 10 pages. Kapteyn, J. C. 1897b. Stern mit grosster¨ bislang bekannter Eigenbewegung. Astronomische Nachrichten 145, 159. [1898AN....145..159K] Gill, D. & Kapteyn, J. C. 1897. The Cape Photographic Durchmusterung for the equinox 1875. Part II. Zones −38◦ to −52◦. Annals of the Cape Observatory, South Africa, 4, 1–702. [1897AnCap...4....1G] Kapteyn, J. C. 1898a. Bestimmung von 250 Parallaxen. Astronomische Nach- richten 145, 289–300. [1898AN....145..289K] Kapteyn, J. C. 1898b. Die mittlere Geschwindigkeit der Sterne, die Quantitat¨ der Sonnenbewegung und die mittlere Parallaxe der Sterne von verschiedener Grosse¨ . Astronomische Nachrichten 146, 97–114. [1898AN....146...97K] Kapteyn, J. C. 1898c. Bemerkungen zu der Abhandlung des Herrn J. Scheiner “Uber¨ die Abhangigkeit¨ der Grossenangaben¨ der Bonner Durchmusterung von der Sternfulle”¨ in Astr. Nachr. Nr. 3505. Astronomische Nachrichten 147, 305–310. [1898AN....147..305K] Gill, D. & Kapteyn, J. C. 1898. The Cape Photographic Durchmusterung.Vier- telsjahrschrift der Astronomiche Gesellsschaft, 33, 192–221. 616 A Publications, Honors and Academic Genealogy

Kapteyn, J. C. 1899. Bemerkungen uber¨ die Beziehung der photographischen und visuellen Grossen¨ der Sterne. Astronomische Nachrichten 150, 103–106. [1899AN ....150.. 103K] Gill, D. & Kapteyn, J. C. 1900. The Cape Photographic Durchmusterung for the equinox 1875. Part III. Zones −53◦ to −89◦. Annals of the Cape Observatory, South Africa, 5, 1–757. [1899AnCap...5....1G] Kapteyn, J. C. & Donner, A. S. 1900. The parallax of 248 stars of the region around B.D. 35,4013. Publications of the Astronomical Laboratory at Groningen 1, 1–87. [1900PGro....1....3K] de Sitter, W. 1900a. On the systematic difference, depending on Galactic latitude, between the photographic and visual magnitudes of stars. Publications of the Astronomical Laboratory at Groningen, 2, 1–22. [1900PGro....2....1D] de Sitter, W. 1900b. On isochromatic plates. Publications of the Astronomical Laboratory at Groningen, 3, 23–36. [1900PGro....3...23D] Kapteyn, J. C. 1900b. Over de bepaling van de coordinaten¨ van het apex der zonsbeweging. Koninklijke Akademie van Wetenschappen, Zittingsverslag 27 Jan- uari 1900, 22 pages. Kapteyn, J. C. 1900c. The determination of the apex of the solar motion. Konin- klijke Nederlandse Akademie van Wetenschappen Proceedings Series B Physical Sciences 2, 353–374. [1899KNAB....2..353K, www.dwc.knaw.nl/DL/publications/ PU00014484.pdf] Kapteyn, J. C. & Kapteyn, W. 1900. On the distribution of cosmic velocities. Part I. Theory. Publications of the Astronomical Laboratory at Groningen 5, 1–87. [1900PGro....5....1K] Kapteyn, J. C. 1900d. Components τ and υ of the proper motions and other quantities for the stars of Bradley. Publications of the Astronomical Laboratory at Groningen 7, 5–120. [1900PGro....7D...5K] Kapteyn, J. C. 1900e. On the mean parallax of stars of determined proper motion and magnitude. Publications of the Astronomical Laboratory at Groningen 8, 1–31. [1900PGro....8....1K] Kapteyn, J. C. 1901a. De lichtkracht der vaste sterren. Koninklijke Akademie van Wetenschappen, Zittingsverslag 20 April 1901, 32 pages. Kapteyn, J. C. 1901b. Der Apex der Sonnenbewegung, die Constante der Prae- cession und die Correctionen der Eigenbewegungen in Declination von Auwers- Bradley. Astronomische Nachrichten 156, 1. [1901AN....156....1K] Kapteyn, J. C. 1901c. Beantwoording der kritiek van Dr. J. Stein, S.J.. Koninklij- ke Akademie van Wetenschappen, Zittingsverslag 26 October 1901, 11 pages. Kapteyn, J. C. 1901d. Uber¨ die Bewegung der Nebel in der Umgebung von Nova Persei. Astronomische Nachrichten 157, 201–204. [1901AN....157..201K] Kapteyn, J. C. 1901e. Methode´ statistique pour la determination´ de l’apex du mouvement solaire. Archives Neerlandaises´ des Sciences Exactes et Naturelles (Hollandsche Maatschappij der Wetenschappen), Ser. II, Tome VI, 262–284. Kapteyn, J. C. 1901f. Over de afstandsbepaling van de hemelichamen. Popular lecture. A.1 Publications by J.C. Kapteyn 617

Fig. A.3 In the ﬁrst volume in Fig. A.2, Kapteyn had pasted a hand-written index to his publications in the three blue volumes. In each he provided a continuous numbering of the pages. The list was systematic by subject. It has been produced around 1916, at least that is the date of the last paper in the collection. Here I reproduce the ﬁrst page (Kapteyn Astronomical Institute)

Kapteyn, J. C. 1901g. On the luminosity of the ﬁxed stars. Koninklijke Neder- landse Akademie van Wetenschappen Proceedings Series B Physical Sciences 3, 658–689. [1900KNAB....3..658K; www.dwc.knaw.nl/DL/publications/PU00014426. pdf] Kapteyn. J. C. 1902a. Reply to the criticism of Dr. J. Stein, S.J. Koninkli- jke Nederlandse Akademie van Wetenschappen Proceedings Series B Physical Sciences 4, 232–242. [1901KNAB....4..232K; www.dwc.knaw.nl/DL/publications/ PU00014273.pdf] Kapteyn, J. C. 1902b. Components τ and υ of the proper motions and other quantities for the stars of Bradley, Sixth Computation. Publications of the Astronomical Laboratory at Groningen 9, 1–56. [1902PGro....9....1K] Kapteyn, J. C. & Donner, A. S. 1902. The parallax of 248 stars of the region around B.D. 35,4013., Summary by F. Cohn (1866–1922). Vierteljahrsschrift der Astronomischen Gesellschaft, 36, 6–20. Kapteyn, J. C. 1902c. On the mean parallax of stars of determined proper motion and magnitude., Summary by K. Kobold. Vierteljahrsschrift der Astronomischen Gesellschaft, 37, 16–24. 618 A Publications, Honors and Academic Genealogy

Kapteyn, J. C., de Sitter, W. & Donner, A. S. 1902. Parallaxes of the clusters h and χ Persei, of Groombridge 745, 61 Cygni, and surrounding stars. Publications of the Astronomical Laboratory at Groningen 10, 1–59. [1902PGro...10....1K] Kapteyn, J. C. 1902d. On the luminosity of the ﬁxed stars. Publications of the Astronomical Laboratory at Groningen 11, 3–32. [1902PGro...11....3K] Kapteyn, J. C. 1902e. On the motion of nebulae in the vicinity of Nova Persei. Popular Astronomy, 10, 124–127. [1902PA.....10..124K] Kapteyn, J. C. 1902f. Uber¨ die Airy’sche Methode zur Bestimmung des Apex der Sonnenbewegung. Astronomische Nachrichten 159, 121–126. [1902AN....159.. 121K] Gill, D. & Kapteyn, J. C. 1903. Revision of the Cape Photographic Durchmuste- rung, Part II. Variable stars, miscellaneous stars, etc.. Annals of the Cape Observa- tory, South Africa, 9, 2.1–2.188. [1903AnCap...9....2G] Kapteyn, J. C. 1903a. Uber¨ die Deklination des Apex der Sonnenbewegung. Astronomische Nachrichten 161, 325–364. [1903AN....161..325K] Kapteyn, J. C. 1903b. Skew frequency curves in biology and statistics. Noordhof, Groningen, 45 pages + ﬁgures. de Sitter, W. 1904. Investigation of the systematic difference between the photographic and visual magnitudes of stars depending on Galactic latitude, based on photometric observations by W. de Sitter, visual estimates by R.T.A. Innes, and photographs taken at the Cape Observatory, together with catalogues of the photometric and photographic magnitudes of 791 stars.. Publications of the Astronomical Laboratory at Groningen 12, 1–166. [1904PGro...12....1D] Weersma, H. A. 1904. The proper motions of 66 stars of the Hyades derived from the observations of 34 catalogues between 1755 and 1900. Publications of the Astronomical Laboratory at Groningen 13, 1–31. [1904PGro...13....1W] Kapteyn, J. C., de Sitter, W. & Donner, A. S. 1904. The proper motions of the Hyades. Publications of the Astronomical Laboratory at Groningen 14, 1–87. [1904PGro...14D...1K] Kapteyn, J. C. 1904a. Remarks on the determination of the number and mean parallax of stars of different magnitude and the absorption of light in space. Astro- nomical Journal 24, 115–122. [1904AJ.....24..115K] Kapteyn, J. C. 1904b. Statistical methods in stellar astronomy. Presentation at the Louisiana Purchase Exposition (also known as the fourteenth World’s Fair), held at St. Louis, Missouri, International Congress of Arts and Sciences, Vol. VIII: Astron- omy and Earth Sciences, 396–425. Kapteyn, J. C. 1905a. Star Streaming. Report of the British Association for the Advancement of Science, South Africa, 257–265. Kapteyn, J. C. 1905b. Reply to Prof. Pearsons criticism. Recueil des Travaux Botaniques Neerlandais.´ No. 3, 7 pages. Kapteyn, J. C. 1906a. Over de parallax van nevelvlekken. Koninklijke Akademie van Wetenschappen, Zittingsverslag 24 Februari 1906, 9 pages. Kapteyn, J. C. 1906b. On the parallax of the nebulae. Koninklijke Nederlandse Akademie van Wetenschappen Proceedings Series B Physical Sciences 8, 691–699. [1905KNAB....8..691K; www.dwc.knaw.nl/DL/publications/PU00013906.pdf] A.1 Publications by J.C. Kapteyn 619

Kapteyn, J. C. 1906c. Sur la parallaxe des nebuleuses´ , Archives Neerlandaises´ des Sciences Exactes et Naturelles (Hollandsche Maatschappij der Wetenschappen), Ser. II, Tome XI, 502–511. Kapteyn, J. C. 1906d. Plan of Selected Areas. Astronomical Laboratory at Groningen, Hoitsema Brothers, Groningen. Kapteyn, J. C. 1906e. Courants dans la Systeme´ Stellaire, Archives Neerlandaises´ des Sciences Exactes et Naturelles (Hollandsche Maatschappij der Wetenschappen), Ser. II, Tome XI, 32–54. de Sitter, W. 1906. Tables for photographic parallax observations. Publications of the Astronomical Laboratory at Groningen 15, 1–12. [1906PGro...15....1D] Kapteyn, J. C. & Kapteyn, W. 1906. Some useful trigonometrical formulae and a table of goniometrical functions for the four quadrants. Publications of the Astro- nomical Laboratory at Groningen 16, 13–19. Kapteyn, J. C. 1908a. Over de gemiddelde sterdichtheid op verschillende afstand van het zonnestelsel. Koninklijke Akademie van Wetenschappen, Zittingsverslag 29 Februari 1909, 10 pages. Kapteyn, J. C. 1908b. On the mean star-density at different distances from the solar system. Koninklijke Nederlandse Akademie van Wetenschappen Proceedings Series B Physical Sciences 10, 626–635. [1907KNAB...10..626K; www.dwc.knaw. nl/DL/publications/PU00013684.pdf] Kapteyn, J. C. 1908c. Sur la densite´ moyenne a´ des distances differentes´ du Systeme´ Solaire, Archives Neerlandaises´ des Sciences Exactes et Naturelles (Hollandsche Maatschappij der Wetenschappen), Ser. II, Tome XIII, 458–470. Kapteyn, J. C. 1908d. On the number of stars of determined magnitude and determined Galactic latitude. Publications of the Astronomical Laboratory at Groningen 18, 1–54. [1908PGro...18....1K] Kapteyn, J. C., de Sitter, W.& Donner, A. S. 1908a. The proper motions of 3300 stars of different Galactic latitudes. Publications of the Astronomical Laboratory at Groningen 19, 1–42 and T1-T112. [1908PGro...19D...1K] Kapteyn, J. C., de Sitter, W. & Donner, A. S. 1908b. The parallaxes of 3650 stars of different Galactic latitudes, with an appendix containing rules for the treatment of parallax-plates and a graphical table of parallax-coefﬁcients. Pub- lications of the Astronomical Laboratory at Groningen 20, 1–34 and T1-T136. [1908PGro...20....1D] Weersma, H. A.. 1908. A determination of the apex of the Solar motion according to the method of Bravais. Publications of the Kapteyn Astronomical Laboratory at Groningen, 1–74 and I-XXXI. [1908PGro...21....1W] Kapteyn, J. C. 1908e. Recent researches in the structure of the Universe.Pro- ceedings of the Royal Institution of Great Britain, 16 pages. Kapteyn, J. C. 1908f. Recent researches in the structure of the Universe.The Observatory 31, 346–348. [1908Obs....31..346K] Yntema, L. 1909. On the brightness of the sky and the total amount of starlight. Publications of the Kapteyn Astronomical Laboratory at Groningen, 22, 1–55. [1909PGro...22....1Y] 620 A Publications, Honors and Academic Genealogy

Kapteyn, J. C., de Sitter, W., Donner, A. S. & Küstner, K. F. 1909. The parallax of the Hyades. Publications of the Astronomical Laboratory at Groningen 23, 1–56. [1909PGro...23....1K] Kapteyn, J. C. 1909a. Recent researches in the structure of the universe. Annual Report of the Smithsonian Institution 1909, 301–320. [ia600502.us.archive.org/17/ items/annualreportofbo1908smitfo/annualreportofbo1908smitfo.pdf]. Kapteyn, J. C. 1909b. De theorie van eb en vloed. Lezing gehouden op 27 Febru- ari 1909, Jaarboekje 1909–1910 de van Mijnbouwkundige Vereeniging te Delft. 5 pages + figures. Kapteyn, J. C. 1909c. On the absorption of light in space. Astrophysical Jour- nal 29, 46–54. Also: Contributions from the Mount Wilson Observatory, Carnegie Institution of Washington No. 31. [1909ApJ....29...46K] or [1909CMWCI..31....1K] Kapteyn, J. C. 1909d. On the absorption of light in space. Second Paper. As- trophysical Journal 30, 284–317. Also: Contributions from the Mount Wilson Ob- servatory, Carnegie Institution of Washington No. 42. [1909ApJ....30..284K] or [1909CMWCI..42....1K] Kapteyn, J. C. 1909e. Correction to Professor Kapteyn’s article in the November Number. Astrophysical Journal 30, 398–399. [1909ApJ....30..398K] Kapteyn, J. C. & Weersma, H. A. 1910. List of parallax determinations. Publica- tions of the Astronomical Laboratory at Groningen 24, 1–32. [1910PGro...24....1K] Kapteyn, J. C. 1910a. The luminosity curve. Astronomische Nachrichten 183, 313–332. [1910AN....183..313K] Kapteyn, J. C. 1910b. On certain statistical data which may be valuable in the classification of the stars in the order of their evolution. Astrophysical Journal 31, 258–269. Also: Contributions from the Mount Wilson Observatory, Carnegie Insti- tution of Washington No. 45. [1910ApJ....31..258K] or [1910QB1.C32n45.....] Kapteyn, J. C. & Frost, E. B. 1910. On the velocity of the Sun’s motion through space as derived from the radial velocity of Orion stars. Astrophysical Journal 32, 83–90. [1910ApJ....32...83K] Kapteyn, J. C. 1910c. On the average parallax of the stars of the fourth type as compared with that of stars of other types. Astrophysical Journal 32, 91–95. [1910ApJ....32...91K] Kapteyn, J. C. 1910d. On the systematic proper motion of the Orion stars. Evening addresses delivered to the Solar Union, Transactions of the International Union for Cooperation in Solar Research, 3, 215–231. [1910TIUCS...3..201.] Kapteyn, J. C. 1911a. De melkweg en de sterstroomen. Koninklijke Akademie van Wetenschappen, Zittingsverslag 25 November 1911, 8 pages. Kapteyn, J. C. 1911b. The Milky Way and the star-streams. Koninklijke Nederlandse Akademie van Wetenschappen Proceedings Series B Physical Sci- ences 14, 524–530. [1911KNAB...14..524K; www.dwc.knaw.nl/DL/publications/ PU00013176.pdf] Kapteyn, J. C. & Frost, E. B. 1911. Correction. Astrophysical Journal 33, 86. [1911ApJ....33...86K] Kapteyn, J. C., 1911c. First and second report on the progress of the Plan of Selected Areas. Hoisema Brothers, Groningen. A.1 Publications by J.C. Kapteyn 621

Fig. A.4 Books in the Kapteyn Room. This shelve shows a collection of the Publications of the Kapteyn Astronomical Laboratory Groningen. This set was originally available in the ofﬁce of the director (respectively Kapteyn, P.J. van Rhijn and A. Blaauw) (Kapteyn Astronomical Institute)

Kapteyn, J. C. 1911d. Een paar nieuwere onderzoekingen op het gebied der evolutie van de vaste sterren en het sterrenstelsel. Handelingen van het XIIIe Ned- erlandsch Natuur- en Geneeskundig Congres, gehouden te Groningen op 20, 21 en 22 April 1911, 44–68. van Maanen, A., 1911. The proper motions of 1418 stars in and near the clusters h and χ Persei. Recherches Astronomiques de l’Observatoire d’Utrecht, 5, v-99. [1911RAOU....5....1V] Kapteyn, J. C. 1912a. Deﬁnition of the correlation-coefﬁcient. Monthly Notices of the Royal Astronomical Society 72, 518–525. [1912MNRAS..72..518K] Kapteyn, J. C. 1912b. Star systems and the Milky Way. Koninklijke Nederlandse Akademie van Wetenschappen Proceedings Series B Physical Sciences 14, 909– 911. [1911KNAB...14..909K; www.dwc.knaw.nl/DL/publications/PU00013254.pdf] Kapteyn, J. C. & Weersma, H. A. 1912. On the derivation of the constants for the two star streams. Monthly Notices of the Royal Astronomical Society 72, 743–756. [1912MNRAS..72..743K] Kapteyn, J. C. 1912c. Tree-growth and meteorological factors. Private publication, 27 pages. Kapteyn, J. C. 1913a. The structure of the Universe. Science 38, 717–724. [1913Sci....38..717K] Kapteyn, J. C. 1913b. On the structure of the Universe. Scientia 14, 245–357. Kapteyn, J. C. & Weersma, H. 1914. The proper motions of 3714 stars derived from plates taken at the observatories of Helsingfors and Cape of Good Hope. Pub- lications of the Astronomical Laboratory at Groningen 25, 1–28, H1-H13. Kapteyn, J. C. 1914a. On the structure of the universe. Journal of the Royal Astronomical Society of Canada 8, 145–159. [1914JRASC...8..145K] Smid, E. I. 1914. Bepaling der eigenbeweging in Rechte Klimming en Declinatie van 119 sterren., Ph.D. Thesis, University of Groningen. 622 A Publications, Honors and Academic Genealogy

Kapteyn, J. C. 1914b. On the individual parallaxes of the brighter Galactic helium stars in the southern hemisphere, together with considerations on the parallax of stars in general. Astrophysical Journal 40, 43–126. Also: Contributions from the Mount Wilson Observatory No. 82. [1914ApJ....40...43K] or [1914CMWCI..82 ....3K] Kapteyn, J. C. 1914c. Sir David Gill. Astrophysical Journal 40, 161–172. [1914 ApJ ....40..161K] Kapteyn, J. C. 1914d. On the change of spectrum and color index with distance and absolute brightness. Present state of the question. Astrophysical Journal 40, 187–204. Also: Contributions from the Mount Wilson Observatory, Carnegie Insti- tution of Washington No. 83. [1914ApJ....40..187K] or [1914CMWCI..83....1K] Kapteyn, J. C. 1914e. Het sterrekundig laboratorium. Academia Groningana MDCXIV-MCMXIV: Gedenkboek ter gelegenheid van het derde eeuwfeest der Universiteit te Groningen, 550–552, Kapteyn, J. C. 1915. On a device for avoiding systematic errors depending on magnitude in the measurement of stellar photographs. Astrophysical Journal 41, 77–80. [1915ApJ....41...77K] Kapteyn, J. C. & Adams, W. S. 1915. The relations between the proper motions and the radial velocities of the stars of the spectral types F,G, K, and M. Proceedings of the National Academy of Science 1, 14–21. [1915PNAS....1...14K] Kapteyn, J. C. & van Uven, M. J. 1916. Skew frequency curves in biology and statistics, 2nd paper. Astronomical Laboratory at Groningen, Hoitsema Brothers, Groningen, 69 pages + ﬁgures. Kapteyn, J. C. 1916. Skew frequency curves in biology and statistics. Recueil des Travaux Botaniques Neerlandais,´ XIII, Livr. II, 105–157. van Rhijn, P. J. 1916a. The proper motions of the stars in and near the Praesepe cluster, derived from photographic plates taken at Potsdam. Publications of the Kap- teyn Astronomical Laboratory at Groningen, 26, 1–24. [1916PGro...26....1V] van Rhijn, P. J. 1916b. The change of color with distance and apparent magnitude together with a new determination of the mean parallaxes of the stars of given magnitude and proper motion. Astrophysical Journal, 43, 36–42. Also: Contribu- tions from the Mount Wilson Observatory, Carnegie Institution of Washington No. 110. [1916ApJ....43...36V] and [1916CMWCI.110....1V] Meijering, S. C. 1916. On the systematic motions of the K-stars. PhD Thesis, University of Groningen. van Rhijn, P. J. 1917. On the number of stars of each photographic magnitude in different Galactic latitudes. Publications of the Kapteyn Astronomical Laboratory at Groningen, 27, 1–63. [1916PGro...27....1V] Pickering, E. C. & Kapteyn, J. C. 1918. Durchmusterung of Selected Areas between δ = 0◦ and δ =90◦; Systematic Plan. Annals of Harvard College Observatory 101, 1–368. [1918AnHar.101....1P] Kapteyn, J. C. & van Rhijn, P. J. 1918. The proper motion of 2380 stars derived from plates taken at the Royal Observatory, Cape of Good Hope. Publications of the Astronomical Laboratory at Groningen 28, 1–51. A.1 Publications by J.C. Kapteyn 623

Kapteyn, J. C., van Rhijn, P. J. & Weersma, H. 1918. The secular parallax of the stars of different magnitude, Galactic latitude and spectrum. Publications of the Astronomical Laboratory at Groningen 29, 1–63. [1918PGro...29Q...1.] and [1918PGro...29...45.] Kapteyn, J. C. 1918a. On the parallaxes and motion of the brighter Galactic helium stars between Galactic longitudes 150◦ and 216◦. Astrophysical Journal 47, 104–133. Also: Contributions from the Mount Wilson Observatory, Carnegie Insti- tution of Washington No. 147. [1918ApJ....47..104K] or [1918CMWCI.147....3K] Kapteyn, J. C. 1918b. On the parallaxes and motion of the brighter Galactic helium stars between Galactic longitudes 150◦ and 216◦ – Continued. Astro- physical Journal 47, 146–178. Also: Contributions from the Mount Wilson Ob- servatory, Carnegie Institution of Washington No. 147. [1918ApJ....47..146K] or [1918CMWCI.147....3K] Kapteyn, J. C. 1918c. On the parallaxes and motion of the brighter Galac- tic helium stars between Galactic longitudes 150◦ and 216◦ – Concluded. Astro- physical Journal 47, 255–282. Also: Contributions from the Mount Wilson Ob- servatory, Carnegie Institution of Washington No. 147. [1918ApJ....47..255K] or [1918CMWCI.147....3K] Schouten, W. J. A. 1918. On the determination of the principal laws of statistical astronomy. PhD Thesis, University of Groningen. van Rhijn, P. J. 1919. On the brightness of the sky at night and the total amount of starlight. Astrophysical Journal, 50, 356–375. Also: Contributions from the Mount Wilson Observatory, Carnegie Institution of Washington No. 173, 1–20. [1919ApJ....50..356V] or [1919CMWCI.173....1V] Kapteyn, J. C. & van Rhijn, P. J. 1920a. Numbers of stars between deﬁnite lim- its of magnitude, proper motion and Galactic latitude for each spectral class, together with some other investigations., Publications of the Astronomical Laboratory at Groningen 30, 1–110. [1920PGro...30....1.] Kapteyn, J. C. & van Rhijn, P. J. 1920b. On the distribution of the stars in space especially in the high Galactic latitudes. Astrophysical Journal 52, 23–38. Also: Contributions from the Mount Wilson Observatory, Carnegie Institution of Washington No. 188. [1920ApJ....52...23K] or [1920CMWCI.188....1K] ten Bruggen Cate, G. H. Determination and discussion of the spectral classes of 700 stars mostly near the North Pole. PhD Thesis, University of Groningen. Kapteyn, J. C. 1921. Proeve eener theorie van de rangschikking en de beweg- ing van het groote sterrenstelsel., ‘Physica’, Nederlandsch Tijdschrift voor Natuur- kunde, 1, 352–356. vanRhijn,P.J.On the brightness of the sky at night and the total amount of starlight, Publications of the Kapteyn Astronomical Laboratory at Groningen, 31, 1–83. [1921PGro...31....1V] Kapteyn, J. C. & van Rhijn, P. J. 1922a. The proper motions of δ Cephei stars and the distances of the globular clusters. Bulletin of the Astronomical Institutes of the Netherlands 1, 37–42. [1922BAN.....1...37K] Kapteyn, J. C. & van Rhijn, P. J. 1922b. On the upper limit of the distance to which the arrangement of stars in space can at present be determined with 624 A Publications, Honors and Academic Genealogy some conﬁdence. Astrophysical Journal 55, 242–271. Also: Contributions from the Mount Wilson Observatory, Carnegie Institution of Washington 229, 1–30. [1922ApJ....55..242K] or [1922CMWCI.229....1K] Kapteyn, J. C. 1922a. First attempt at a theory of the arrangement and motion of the Sidereal System. Astrophysical Journal 55, 302–328. Also: Contributions from the Mount Wilson Observatory, Carnegie Institution of Washington No. 230. [1922ApJ....55..302K] or [1922CMWCI.230....1K] Kapteyn, J. C. 1922b. On the proper motions of the faint stars and the systematic errors of the Boss fundamental system. Bulletin of the Astronomical Institutes of the Netherlands 1, 69–78. [1922BAN.....1...69K] Pickering, E. C., Kapteyn, J. C. & van Rhijn, P. J. 1923. Durchmusterung of Selected Areas: δ = −15◦ and −30◦; Systematic Plan. Annals of Harvard College Observatory 102, 1–276. [1923AnHar.102....1P] Pickering, E. C., Kapteyn, J. C. & van Rhijn, P. J. 1924. Durchmusterung of Selected Areas: δ = −45◦ and −90◦; Systematic Plan. Annals of Harvard College Observatory 103, 1–340. [1924AnHar.103....1P] Seares, F. H., van Rhijn, P. J., Joyner, M. C. & Richmond, M. L. 1925. Mean distribution of stars according to apparent magnitude and Galactic latitude.Astro- physical Journal, 62, 320–374. [1925ApJ....62..320S] Seares, F. H., Kapteyn, J. C., van Rhijn, P. J., Joyner, M. C. & Richmond, M. L. 1930. Mount Wilson Catalogue of photographic magnitudes in Selected Areas 1–139. Carnegie institution of Washington. Monnichmeyer,¨ C. O. L., Kapteyn, J. C., Hopmann, J. & Schaub, W. 1930. Kata- log von 1172 Sternen in Kapteyn’s “Selected Areas” auf Grund der Beobachtungen am Repsoldschen Meridiankreise. Veroffentlichungen¨ des Astronomisches Institute der Universitat¨ Bonn 21, 1–40. [1930VeBon..21....1M] van Rhijn, P. J. & Kapteyn, J. C. 1952. Durchmusterung of Selected Areas of the Special Plan. Kapteyn Astronomical Laboratory at Groningen.

A.2 Publications About Kapteyn

Articles. Glaisher, J. W. L. 1902. Address delivered by the President, Dr. J.W.L. Glaisher, on presenting the Gold Medal to Professor J.C. Kapteyn. Monthly Notices of the Royal Astronomical Society, 62, 334–343 [1902MNRAS..62..329.] Galloway, J. D. 1902. Kapteyn’s contributions to our knowledge of the stars. Publications of the Astronomical Society of the Paciﬁc, 14, 97–102 [1902PASP...14 ...97G] Curtis, H. D. 1913. Address of the retiring President of the Society in award- ing the Bruce Medal to Professor J.C. Kapteyn. Publications of the Astronomical Society of the Paciﬁc, 25, 15–27 [1913PASP...25...15C] van Rhijn, R. J. 1921. De bouw van het sterrenstelsel: Kapteyn’s beteekenis voor de moderne astronomie. De Gids, Juli 1921, 128–144. A.2 Publications About Kapteyn 625

van Rhijn, P. J. 1922. Jacobus Cornelius Kapteyn. In memoriam. Popular Astron- omy, 30, 628–631. [1922PA.....30..628V] Eddington, S. A. 1922. Jacobus Cornelius Kapteyn. The Observatory, 45, 261–265. [1922Obs ....45..261.] van Maanen, A. 1922. J.C. Kapteyn, 1851–1922. Astrophysical Journal, 56, 145–153. [1922ApJ....56..145V] Seares, F. H. 1922. J.C. Kapteyn. Publications of the Astronomical Society of the Paciﬁc, 34, 233–253. [1922PASP...34..233S] de Sitter, W. 1922. Jacobus Cornelius Kapteyn †(19 Januari 1851–18 Juni 1922). Hemel & Dampkring 20, 97–111. Easton, C. 1922 Persoonlijke herinneringen aan J.C. Kapteyn. Hemel & Damp- kring, 20, 112–117 and 151–164. Pannekoek, A. 1922a. J.C. Kapteyn und sein astronomische Werk. Die Naturwis- senschaften, Heft 45, 1–14. Pannekoek, A. 1922b. J.C. Kapteyn en zijn astronomisch werk. Wetenschappeli- jke Bladen I., 257–295. de Sitter, W. 1923. Jacobus Cornelius Kapteyn. 19. Januar 1851 bis 18. Juni 1922. Vierteljahrsschrift der Astronomischen Gesellschaft, 58, 162–190 (1923). Jeans, J. 1923. Obituary Notices : Associates :- Kapteyn, Jacobus Cornelius. Monthly Notices of the Royal Astronomical Society, 83, 250–255. van Rhijn, P. J. 1951. J.C. Kapteyn Centennial. Sky & Telescope, 10, 55–57. [1951S&T.... 10...55V] Dekker, E. 1978. Kapteyn en de studie van de hoogere deelen des hemels. Zenit 5, 448–453. Dekker, E. 1983. Jacobus Cornelius Kapteyn (1851–1922). In: ‘Sterrenkijken bekeken: Sterrenkunde aan de Groningse universiteit vanaf 1614’, by A. Blaauw, J.A. de Boer, E. Dekker and J. Schuller tot Peursum-Meijer, Museum of the Univer- sity of Groningen Paul, E. R. 1981. The death of a research programme – Kapteyn and the Dutch astronomical community. Journal for the History of Astronomy, 12, 77–94. [1981JHA....12...77P] Paul, E. R. 1985. Kapteyn and statistical astronomy. The Milky Way Galaxy, Proceedings of I.A.U. Symposium No. 106, held May 30-June 3 1983 in Groningen, the Netherlands, p.25–42. [1985IAUS..106...25P] Paul, E. R. 1986. Kapteyn and the early twentieth-century universe. Journal for the History of Astronomy, 17, 155–182 [1986JHA....17..155P] Tenn, J. S. 1991. Bruce Medalist Proﬁles - Kapteyn, Jacobus. Mercury, 20, 145–147. [1991Mercu..20..145T]

Books. H. Hertzsprung-Kapteyn: J.C. Kapteyn; Zijn leven en werken. P. Noordhoff, Groningen (1928). E. Robert Paul: The Milky Way Galaxy and statistical cosmology, 1890–1924. Cambridge Univ. Press, Cambridge (1993), ISBN 0-5213-5363-7. 626 A Publications, Honors and Academic Genealogy

P. C. van der Kruit & K. van Berkel: The Legacy of J.C. Kapteyn: Kapteyn and the development of modern astronomy. Kluwer Academic Publishers, Dordrecht (2000), ISBN 0-7923-6393-0. K. van Berkel & A. Noordhof-Hoorn: Lieve Lize: De minnebrieven van de Groningse astronoom J.C. Kapteyn aan Elise Kalshoven, 1878–1879. University of Groningen (2008), ISBN 978-90-367-3353-3.

A.3 Kapteyn and His School: PhD Theses up to 1946

Below I present a listing of the PhD theses that can be seen as belonging to the school (students of Kapteyn and students of students) and legacy of Kapteyn. I include theses defended up to 1946 in Groningen, Leiden and Utrecht. Theses under de Sitter on the satellites of Jupiter and of other objects have also been excluded. In Groningen under the supervision of J. C. Kapteyn: WILLEM DE SITTER (17 May, 1901): Discussion of heliometer-observations of Jupiter’s satellites made by Sir David Gill, K.C.B. and W.H. Finlay. CORNELIS EASTON (1903): Doctor Honoris Causa. HERMAN ALBERTUS WEERSMA (9 July, 1908): A determination of the solar motion according to the method of Bravais. LAMBERTUS YNTEMA (17 December 1909): On the brightness of the sky and the total amount of starlight. ETINE IMKE SMID (13 June, 1914): Bepaling der eigenbeweging in rechte klimming en declinatie van 119 sterren (Determination of the proper motion in right ascension and declination for 119 stars). PIETER JOHANNES VAN RHIJN (9 July, 1915): Derivation of the change of colour with distance and apparent magnitude together with a new determination of the mean parallaxes of the stars with given magnitude and proper motion. SAMUEL¨ CORNELIS MEIJERING (6 July, 1916): On the systematic motions of the K-stars. WILLEM JOHANNES ADRIAAN SCHOUTEN (4 July, 1918): On the determination of the principal laws of statistical astronomy. GERRIT HENDRIK TEN BRUGGEN CATE (24 June, 1920): Determination and discussion of the spectral classes of 700 stars mostly near the north pole. In Utrecht, under the supervision of A. A. Nijland2: ADRIAAN VAN MAANEN (June 2, 1911): The proper motions of 1418 stars and near the clusters h and χ Persei (initiated by and with major involvement of Kapteyn). ISIDORE HENRI NORT (October 15, 1917): The Harvard map of the sky and the Milky Way.

2The thesis by Allard Othumar Holwerda (16 May, 1913): Frequentiecurven (Frequency curves) is sometimes attributed to Kapteyn, but in fact it was written under the supervision of his brother Willem. Although Kapteyn’s 1903 article on Skew Frequency Curves is discussed, no direct involvement of him with this work is apparent. A.3 Kapteyn and His School: PhD Theses up to 1946 627

Fig. A.5 Two of Kapteyn’s students: Pieter van Rhijn and Willem de Sitter at the dinner on the occasion of the PhD defense of Jan Oort in Groningen, May 1926. The woman next to de Sitter (sitting) is Mrs de Sitter; the woman standing next to van Rhijn is Oort’s future mother-in-law (see also Fig. 12.1) (Photograph Leids Fotoarchief, Sterrewacht Leiden)

JAN CORNELIS VAN DE LINDE (4 November 1921): De verdeeling van de heldere sterren (The distribution of the bright stars).

In Groningen under the supervision of van P. J. Rhijn: EGBERT ADRIAAN KREIKEN (21 February, 1923): On the colour of the faint stars in the Milky Way and the distance of the Scutum group. JAN SCHILT (21 May, 1924): On a thermo-electric method of measuring photographic magnitudes. JAN HENDRIK OORT (1 May, 1926): The stars of high velocity. PETER VAN DE KAMP (30 November, 1926): De Zonsbeweging met betrekking tot apparent zwakke sterren (The motion of the Sun with respect to apparently faint stars). WILLEM JAN KLEIN WASSINK (21 March, 1927): The proper motion and the distance of the Praesepe cluster. 628 A Publications, Honors and Academic Genealogy

BARTHOLOMEUS JAN BOK (6 July, 1932): A study of the η Carinae region. JEAN JACQUES RAIMOND (10 July, 1933): The coefﬁcient of differential galactic absorption. BROER HIEMSTRA (18 May, 1938): Dark clouds in Kapteyn’s special areas 2, 5, 9 and 24 and the proper motions of the stars in these regions. ADRIAAN BLAAUW (6 July, 1946): A study of the Scorpio-Centaurus cluster.

In Leiden under the supervision of W. de Sitter: WILLEM HENDRIK VAN DEN BOS (7 July, 1925): Micrometingen van dubbelster- ren (Micrometer measurements of binary stars). COERT HENDRIK HINS (15 December, 1925): Inleiding tot een catalogus van plaatsen en eigenbewegingen van 1533 roode sterren (Introduction to a catalogue of positions and proper motions of 1533 red stars).

In Leiden under the supervision of E. Hertzsprung: WILLEM JACOB LUYTEN (1 July, 1921): Observations of variable stars. ◦ HENDRIK VAN GENT (8 April, 1932): Veranderlijke sterren op een veld van 10 bij 10◦ in of nabij het sterrenbeeld Corona Australis (Variable stars in a ﬁeld of 10◦ by 10◦ in or near to the constellation Corona Australis). PIETER THEODORUS OOSTERHOFF (6 April, 1933): Effectieve golﬂengten en photographische magnituden van sterren in h en χ Persei (Effective wavelengths and photographic magnitudes of stars in h and χ Persei). GERRIT PIETER KUIPER (30 June, 1933): Statistische onderzoekingen van dubbel- sterren (Statistical studies of double stars). AERNOUT DE SITTER (29 June, 1936): Fotovisueele fotometrie van sterren tot 8.0 magnituden benoorden +80◦ declinatie (Photovisual photometry of stars to magnitude 8.0 north of declination +80◦). WILLEM CHRISTIAAN MARTIN (11 May, 1937): Photographische photometrie van veranderlijke sterren in Centaurus (Photographic photometry of variable stars in Centaurus). ADRIAAN JAN WESSELINK (13 May, 1938): Photographische photometrie met toepassing op de veranderlijke ster SZ Camelopardalis (Photographic photometry with application to the variable star SZ Camelopardalis). LUCAS PLAUT (2 May, 1939): Photographische photometrie der veranderlijke sterren CV Carinae en WW Draconis (Photographic photometry of the variable stars CV Carinae en WW Draconis). JACOBUS GIJSBERTUS FERWERDA (3 October 1941): Veranderlijke sterren in de omgeving van Sagittarius (Variable stars in the neighborhood of Sagittarius).

In Leiden under the supervision of J. H. Oort: GIJSBERT VAN HERK (1 May, 1936): Enige uitkomsten van de waarnemingen in de jaren 1931–1933 te Equador (Some results of observations made in Ecuador from 1931 to 1933). A.4 Kapteyn’s Honors 629

Fig. A.6 Knighthoods of Kapteyn. From left to right: Knight Ordre National de Legion´ d’Honneur (1892), Knight Order of the Netherlands Lion (1903), Orden Pour le Merite´ (1915) and Comman- der Order of Oranje-Nassau (1921) (Boerhaave Museum, Leiden [5])

A.4 Kapteyn’s Honors

The following list of honors of Kapteyn is translated from the obituary by de Sitter in Hemel & Dampkring 20, 97–111 (1922). Some editing of obvious errors was done, as well as providing more years of award than in the original list. Kapteyn’s great-grandson Jan Willem Noordenbos has shown me a letter from Prof. Adriaan Blaauw to Mrs M.A. Newton in Foxton, Alnmouth, Northumberland, UK, sent from Leiden Observatory on July 14, 1978. Blaauw and Maria Newton– Noordenbos (granddaughter of Kapteyn) had been class mates in high school (see page 579). Apparently replying to a letter from Maria Newton, Blaauw wrote: ‘Thank you for your letter with the information on the distinctions of your grandfather Kapteyn. Be assured that these will be very welcome in the Netherlands. As you maybe remember, I have collected various things that I knew of carefully together and put them in the Kapteyn Laboratory, in the so-called Kapteyn Room. That would be a natural place, but there are two other possibilities: the museum of the university in Groningen might certainly be interested, but I think in the first place of the museum for the history of the natural sciences in general in the Netherlands, which is located here in Leiden. Maybe you do have a preference for one of these, but I will look around some more. I myself think of the latter museum in the first place, since in recent years is has developed many activities in the area of the astronomy of the previous century and even employed an astronomer for that. You write me about the question how to transport the distinctions and the desirability to obtain an export permit. I did not know that it would be so difficult as seen from England; I would have been tempted to just take them in the pocket of my coat, but maybe I am a more experienced smuggler than you are. Do you think there will be an opportunity to bring them to the Netherlands soon?’ Blaauw mentioned that he will travel home late August from Ireland via England. How and when in the end the exchange was accomplished is not clear. In any case, the distinctions ended up in the museum in Leiden mentioned, which now is the Boerhaave Museum. Pictures of the medals are reproduced in Fig.’s A.6 and A.7. 630 A Publications, Honors and Academic Genealogy

Fig. A.7 Medals of Kapteyn, showing in each case front and back. Top row: Gold medal of the R.A.S. (1902) and the Prix Pontecoulant´ (1905). Bottom row: Bruce medal (1913) and the James Craig Watson medal (1913) (Boerhaave Museum, Leiden; see Fig. A.6)

The collection was described in a handwritten note by Mrs Newton-Noordenbos, in which she states her mother Jacoba Cornelia Noordenbos-Kapteyn, Kapteyn’s oldest daughter, left her all this when she died in September 1961. Mrs Newton- Noordenbos wanted to transfer these items to ‘his university’. The inventory also included the text of the speech by Ursul Ph. Boissevain at the occasion of the 40-th anniversary of Kapteyn’s professorship (see page 577) and Kapteyn’s PhD diploma. The list in Hemel & Dampkring is preceded by a note from de Sitter: ‘Kapteyn’s modesty would have objected against a list like this one – that was provided generously by widow Mrs Kapteyn-Kalshoven – would be published. It is however, now a privilege to be able to show how extensively the person and the work of our fellow Dutchman was also respected and treasured.’

Knighthoods and other distinctions: Knight in the Ordre National de la Legion´ d’Honneur, France (1892) Knight in the Order of the Netherlands Lion, the Netherlands (1903) Member of the Orden Pour le Merite´ für Wissenschaften und Künste (1915) Commander in the Order of Oranje-Nassau, the Netherlands (1921) Medals: Gold Medal of the Royal Astronomical Society, London (1902) Prix de Pontecoulant,´ French Academie´ des Sciences de Paris (1905) James Craig Watson Medal, US National Academy of Sciences, Washington (1913) Bruce Medal, Astronomical Society of the Pacific, San Francisco (1913) Honorary Doctorates: Honorary Doctor of Science, Cape of Good Hope (1905) Honorary Doctor of Science, Harvard University, USA (1909) Honorary Doctor of Law, Edinburgh (1921) A.5 Institutions, Objects etc. Named After Kapteyn 631

Memberships: The Netherlands: Royal Netherlands Academy of Arts and Sciences, Amsterdam (1888) Holland Society of Sciences and Humanities, Haarlem (1893) Batavian Society for Experimental Philosophy, Rotterdam (member; 1886; honorary member, 1914) Society of Arts and Sciences of the Province of Utrecht, Utrecht (??) Etcetera Foreign: Foreign Associate of the Royal Astronomical Society, London (1892) Fellow American Philosophical Society, Philadelphia (1907) Foreign Associate American National Academy of Sciences, Washington (1907) Member Imperial Academy of St. Petersburg (1908) Member Royal Academy Dublin (1908) Honorary Member Royal Academy Edinburgh (1910) Corresponding Member British Association, London (1913) Foreign Member Royal Swedish Academy of Sciences, Stockholm (1914) Member Royal Swedish Society of Sciences (Uppsala) (1915) Honorary Member American Society (1915) Membre-correspondant de l’Academie´ des Sciences, Paris (19??) Foreign Member Royal Society, London (1919) Member Finnish Academy of Sciences, Helsingfors (1921) Member Royal Physiographical Society (Lund) (1922)

The Prix de Pontecoulant´ of the French Academie´ des Sciences de Paris is named after French astronomer Philippe Gustave le Doulcet, Comte de Pontecoulant´ (1795–1874). The prize is no longer listed on the Website of the Academie.´

A.5 Institutions, Objects etc. Named After Kapteyn

Three astronomical objects, one institute, one building, one telescope and various streets have been named after Kapteyn; the astronomical objects are a star, a minor planet and a lunar crater. Currently the International Astronomical Union (IAU; see Box 16.1) is the body that decides on names of astronomical objects and bod- ies. However, before the founding of the IAU this was not regulated and observers themselves decided how to name an object. Kapteyn discovered Kapteyn’s Star while working on the Cape Photographic Durchmusterung and reported it in Kapteyn (1897b) in a communication to the Astronomische Nachrichten with the title Stern mit grosster¨ bislang bekannter Eigenbewegung. It had a proper motion (motion on the sky with respect to the ﬁxed stars in general) of about 8.5 arcseconds per year (see Fig. 7.19). For further information on this star see page 237. 632 A Publications, Honors and Academic Genealogy

Fig. A.8 The orbit of minor planet 818 Kapteynia (1916 YZ) relative to the inner Solar System. The image at the top is as seen from a location perpendicular to the plane of the ecliptic (the orbit of the Earth), such that the Earth’s north pole is directed towards the observer. The horizontal line is that through the equinoxes, when the Sun is directly above the Earth’s equator on March 20/21 and September 22/23. The position of the objects is for the date February 21, 1916, the day that the minor planet was discovered by M. Wolf at Heidelberg. The picture at the bottom is the same for an observer in the plane of the ecliptic (Produced with the orbit diagram tool of the JPL Small-Body Database Browser of NASA’s Near-Earth Object (NEO) Project [6])

The minor planet named after Kapteyn was called Kapteynia by Maximilian Franz Joseph Cornelius Wolf (1863–1932), who discovered it on February 21, 1916 at the Landessternwarte Heidelberg-Konigstuhl.¨ The current full designation of the minor planet, is 818 Kapteynia (1916 YZ). It moves around the Sun in a somewhat eccentric elliptical orbit with a semi-major axis of 3.2 AU (one Astronomical Unit AU is the mean distance of the Earth from the Sun of about 150 million km) and makes one revolution around the Sun in 5.64 years (see Fig. A.8, the date of the positions is that of the discovery). The orbit makes an angle of about 16◦ with the plane of the Earth’s orbit and the diameter of the minor planet is 49.5 km. The IAU designated a crater on the Moon with the name Kapteyn in 1964. It is near the limb of the Moon and has a diameter of about 50 km (see Fig. A.9). The institute that is named after Kapteyn is the ‘Astronomical Laboratory’ that he founded himself at the University of Groningen (see Fig. A.10). The building it A.5 Institutions, Objects etc. Named After Kapteyn 633

Fig. A.9 The crater Kapteyn on the Moon photographed from the Apollo 8 spacecraft (NASA image in the public domain [7])

is housed in together with the Laboratory for Space Research, lecture rooms, etc., is now named Kapteynborg [10]. Quite a few cities have named streets after Kapteyn. Barneveld has a Kapteyn- straat at the location of the boarding school ‘Benno’ of his parents (see Fig. A.12). There is also a Kapteynlaan in Groningen and Utrecht, among other places, and a Kapteynstraat in e.g. Leiden, Amsterdam and Hilversum. The Jacobus Kapteyn Telescope (JKT; see Fig. A.13) is a 1-meter telescope on the Observatorio del Roque de los Muchachos of the Instituto de Astrof´ısica de Canarias (IAC) at La Palma, Canary Islands, Spain. It is part of the Isaac Newton Group of Telescopes, to which the 2.5 meter Isaac Newton Telescope and the 4.2 meter William Herschel Telescope also belong. This group of telescopes was built by the United Kingdom and the Netherlands, with the co-operation of Spain. The JKT started operations in 1984, but was closed as a common user facility in 2003 (see R. Laing & D. Jones, The Isaac Newton Group [11]). Then, of course, there is the Kapteyn Cottage at Mount Wilson Observatory near Pasadena in California, where Kapteyn and his wife lived during his visits as a Research Associate. The cottage was ﬁrst used by them in 1910 and their last visit took place in 1914. This is described on page 472 and illustrated in Fig. 13.12. And ﬁnally, since 2013 the Royal Natural Sciences Society (see page 276) has organized an prestigious annual lecture on a subject in the natural or medical sciences under the name of Kapteyn Lecture. 634 A Publications, Honors and Academic Genealogy

Fig. A.10 Part of the Zernike Campus of the University of Groningen, which is located on the northern outskirts of the city. The curved building on the right is Kapteynborg, which houses the Kapteyn Astronomical Institute and the Groningen laboratory of the Netherlands Institute for Space Research. The institute moved to this campus in the late sixties and was originally located in the tall building running from left to right in the middle of the photograph, and moved to its current location in 1983 (Photograph by aerophoto Eelde and University of Groningen [8])

Fig. A.11 The present Kapteynborg. The gray part at the left contains lecture rooms and a restaurant for staff and students of various disciplines located at the Zernike campus; the brown part has the ofﬁces and laboratories of the Kapteyn Astronomical Institute of the University of Groningen and the Netherlands Institute for Space Research of the Netherlands Organization for Scientiﬁc Research (NWO), which are closely collaborating (Photograph by the author) A.6 Academic Genealogy of Kapteyn 635

Fig. A.12 There are various streets in the Netherlands named after Kapteyn. This sign is from the small town of Barneveld, where Kapteyn was born. This street is the entrance to a parking lot near the center of the town, where the boarding house ‘Benno’ was located where Kapteyn was born and raised (Photograph by the author)

Fig. A.13 The Jacobus Kapteyn Telescope on the Roque de los Muchachos, La Palma, Canary Islands (From the Website of the Isaac Newton Group of Telescopes [9])

A.6 Academic Genealogy of Kapteyn

An academic genealogy should ideally follow the PhD theses and advisers. This is not always possible. In the text here a broad interpretation has been adopted. So I have accepted Johann Samuel Konig¨ as a student of the Bernoullis and von Wolff, even though he did not formally submit a PhD thesis; I also ignored the fact that Gerrit Moll received his PhD degree honoris causa. Likewise I have ignored any inconsistencies between the listings in the Mathematics Genealogy Project and 636 A Publications, Honors and Academic Genealogy biographies available on the Web (including those linked to the MGP). I start with my own PhD supervisor and go back in time. [With thanks to Carlo Beenakker [12], Roelof de Jong [13], Manfred Horstmanshoff [14] and the MGP [15]]

Jan Hendrik Oort: Franeker, April 28, 1900 – Leiden, November 5, 1992 – Student of P.J. van Rhijn; PhD thesis: The stars of high velocity, University of Gronin- gen, 1 May 1926. Oort was a professor of astronomy at the University of Lei- den 1935–1970 and director of Leiden Observatory 1946–1970. He won the Bruce Medal in 1942. Pieter Johannes Van Rhijn: Gouda, March 24, 1886 – Groningen, May 9, 1960 – Student of J.C. Kapteyn; PhD thesis: Derivation of the change of colour with distance and apparent magnitude together with a new determination of the mean parallaxes of the stars with given magnitude and proper motion, University of Gro- ningen, July 9, 1915. Van Rhijn was a professor of astronomy at the University of Groningen and director of the Astronomical Laboratory ‘Kapteyn’ 1921–1956. Jacobus Cornelius Kapteyn: Barneveld, January 19, 1851 – Amsterdam, June 18, 1922 – Student of C.H.C. Grinwis; PhD thesis: Onderzoek der trillende platte vliezen (Study of vibrating ﬂat membranes), University of Utrecht, June 24, 1875. Kapteyn was the founder of the Astronomical Laboratory at the University of Groningen, where he was professor of astronomy and theoretical mechanics 1878– 1921. He received the Bruce Medal in 1913.

Cornelis Hubertus Carolus Grinwis: Haarlem, March 9, 1831 – Baarn, December 25, 1899 – Student of R. Van Rees; PhD thesis: De distributione fluidi electrici in superficie conductoris (On the distribution of electricity over the surface of a con- ductor), University of Utrecht, 3 July 1858. Grinwis was a professor of mathematics and physics at the University of Utrecht 1867–1896. Two older brothers of Kapteyn also received a PhD from the University of Utrecht with Grinwis as adviser. Richard van Rees: Nijmegen, May 24, 1797 – Utrecht, August 23, 1875 – Stu- dent of G. Moll; PhD thesis: De celeritate soni per fluida elastica propagati (On the speed of sound in an elastic fluid), University of Utrecht, December 17, 1819. Van Rees was a professor of mathematics and experimental philosophy at the University of Utrecht 1831–1867.

Gerrit (Gerard) Moll: Amsterdam, January 18, 1785 – Amsterdam, January 17, 1838 – Student of J.T. Rossijn; PhD thesis: the degree was awarded honoris causa, University of Utrecht, 28 October 1815. Moll also studied under Jan Hendrik van Swinden (1746–1823) in Amsterdam, where he was a professor of philosophy, physics and astronomy. Moll was a professor of mathematics, astronomy and experimental philosophy 1815–1838 at the University of Utrecht, and director of Utrecht Observatory 1812–1838. Johannes Theodorus Rossijn: Noordzijpe, December 18, 1744 – Utrecht, Decem- ber 24, 1817 – Student of A. Brugmans; PhD thesis: De tonitru et fulmine ex nova electricitatis theoria deducendis (On thunder and lightning according to the new theory of electricity), University of Franeker, 10 December 1762. Rossijn was a A.6 Academic Genealogy of Kapteyn 637 professor of philosophy, mathematics and astronomy at the Universities of Harder- wijk 1765–1775 and Utrecht 1775–1815. Antonius Brugmans: Hantum, October 22, 1732 – Groningen, April 27, 1789 – Student of J.S. Konig;¨ PhD thesis: De phaenomeno (On the phenomenon of), Uni- versity of Franeker, May 24, 1749 – Brugmans is sometimes credited with ‘two philosophical dissertations’ (see H.A. Krop, J.A. van Ruler & A.J. Vanderjagt (edi- tors): Zeer kundige professoren: Beoefening van de filosofie in Groningen van 1614 tot 1996. [16]) with the titles Dissertatio metaphysica de essentiarum, idearumque absoluta necessitate earumque origine ex extellectu divino (Metaphysical dissertation on the absolute necessity of the essentials and of the ideas and their origin in the Divine intellect) (May 25, 1948) and Dissertatio philosophica inauguralis de phaenomeno (Philosophical dissertation on the phenomena, 1749). Brugmans was a professor of philosophy at the University of Franeker 1755–1766 and at the University of Groningen 1766–1789. Johann Samuel Konig¨ :Büdingen, July 31, 1712 – Zuilenstein, August 21, 1757 – Student of Johann and Daniel Bernoulli and Christian Wolff. Konig¨ studied in Basel under Johann from 1730 and under Daniel Bernoulli from 1733. He did not formally receive a PhD degree, but is often considered a student of the Bernoullis. In 1735 he went to study under Christian von Wolff in Marburg. Konig¨ later worked in Bern until he was exiled for his liberal ideas, after which he became a professor of philosophy and mathematics at the University of Franeker 1744–1749. He is the discoverer of Konig’s¨ theorem in kinetics and was the subject of a plagiarism charge related to the principle of least action. Daniel Bernoulli: Groningen, February 8, 1700 – Basel, March 17, 1782 – Stu- dent of Johann Bernoulli(?) ; PhD thesis: Dissertation physico-medica de respira- tione (Dissertation on the medical physics of respiration), University of Basel, 1721. Daniel Bermoulli was a professor of mathematics at the University of St. Petersburg 1725–1733 and a professor of physics at the University of Basel 1750–1776. He developed Bernoulli’s principle in fluid dynamics. Johann Bernoulli: Basel, July 27, 1667 – Basel, January 1, 1748 – Student of Jacob Bernoulli; PhD thesis: Dissertatio physico-anatomica de motu musculorum (Dissertation on the physics and anatomy of muscular motion), University of Basel, 1694. Johann Bernoulli was the younger brother of Jacob. He worked as a professor of mathematics at the University of Groningen 1695–1705. He returned to Basel, where he took over his brother’s chair in mathematics. In 1696 he found the solution for the brachistochrone problem in mechanics, laying the foundation for calculus of variations. Jacob Bernoulli: Basel, December 27, 1654 – Basel, August 16, 1705 – Student of G.W. von Leibniz; PhD thesis: Solutionem tergemini problematis arithmetici, ge- ometrici et astronomici (Solutions to a triple problem in Arithmetics, mathematics and astronomy), University of Basel, February 4, 1684. It is widely accepted that he studied the calculus as introduced by Leibniz. The Bernoulli family had a spice business in Amsterdam. Their Calvinist faith forced them to move to Basel (Switzer- land) in the 1550s when the Spanish occupied Holland. Jacob Bernoulli became a professor of mathematics at the University of Basel 1687–1705. The Bernoulli numbers in mathematics are named after him. 638 A Publications, Honors and Academic Genealogy

Christian von Wolff: Breslau, January 24, 1679 – Halle, April 9, 1754 – Student of E.W. von Tschirnhaus and G.W. von Leibniz; PhD thesis: Dissertatio Algebraica de Algorithmo Infinitesimali Differentiali (Dissertation on the algebra of solving differential equations using infinitesimals), University of Leipzig, 1704. Christian Wolff was a professor of mathematics and natural philosophy at the University of Halle 1706–1723 and 1740–1754 and at Marburg 1723–1740. Ehrenfriend Walter von Tschirnhaus: Kieslingswalde, April 10, 1651 – Gorlitz,¨ 11 October, 1708 – The MGP lists von Tschirnhaus as having obtained the title of Magister philosophiae and Medicinae Doctor at the University of Leiden in 1669 and 1674. Although he did study in Leiden between these years, there is no further evidence that he actually obtained a PhD there (or anywhere else, for that matter). Gottfried Wilhelm von Leibniz: Leipzig, July 1, 1646 – Hannover, November 14, 1716 – Student of E. Weigel; PhD thesis: De casibus perplexis in jure (On perplex- ing cases in law), University of Althof, 1666. Leibniz studied at Jena under Weigel from 1663 onward and wrote a habilitation thesis Dissertatio de arte combinato- ria (Dissertation on the combinatorial art), which was declined by the University of Leipzig. Apparently he received his degree in 1667 at the University of Altdorf, but it is unclear which of the two titles applies and who his adviser was. It seems reasonable to regard Leibniz as a student of Weigel. Leibniz studied mathematics in Paris with Huygens as mentor from 1672 onwards. However, it is unlikely that Huygens had anything to do with a thesis in Altdorf well before 1672. Von Leibniz discovered calculus independently of Newton and invented the mathematical nota- tion we still use. He was a librarian and Court Counselor with the Duke of Hanover from 1676 until his death. Erhard Weigel: Weiden, December 16, 1625 – Jena, March 20, 1699 – Student of P. Muller; ¨ PhD thesis: De ascensionibus et descensionibus astronomicis dissertatio (Astronomical dissertation on risings and settings), University of Leipzig, 1650. Weigel was a mathematician, astronomer and philosopher and is credited with the definition of the date of Easter and promoting the introduction of the Gregorian calendar. He was a professor of mathematics at the University of Jena 1653–1699. Philipp Muller¨ : 1585–1659 – He was the thesis adviser of Erhard Weigel [17] and a professor of mathematics at the University of Leipzig from 1616 onward. Müller may have been a professor of physics as early as 1614 (see H.-J. Girlich and K.-H.Schlote, Die Entwicklung der Mathematik an der Universitat¨ Leipzig [18]). Müller had a keen interest in astronomy and was one of the first to accept Kepler’s laws of planetary motion (see J.L. Russell, Kepler’s Laws of Planetary Motion: 1609–1666 (1964) [19]): ‘Kepler had, however, at least one disciple during the 1620s: Philip Müller, professor of mathematics at the Leipzig University’.He actually corresponded extensively with Johannes Kepler (1571–1630). In his biography of Kepler, Max Caspar (see Max Caspar: Johannes Kepler [20]) describes Jacob Bartsch (ca 1600–1633) as a pupil of Philip Müller’s. Bartsch is known to have made a star chart based on Müller’s data and later became Kepler’s assistant and son-in-law. Appendix B Henriette Hertzsprung-Kapteyn’s Biography of J.C. Kapteyn

To my mother, without whom this life could never have been so complete. Henriette Hertzsprung-Kapteyn1

In 1928 H. Hertzsprung-Kapteyn, daughter of J.C. Kapteyn, wrote a biography of her father, entitled J.C. Kapteyn: Zijn leven en werken, and published it with the publishing company of P. Noordhoff in Groningen. The book is now part of the Digi- tale Bibliotheek voor de Nederlandse Letteren (Digital Library of Dutch Literature), where a complete electronic version of the book is available [1].

B.1 Henriette Hertzsprung–Kapteyn

Henriette Mariette Augustine Albertine Kapteyn (1881–1956) was the second child and second daughter of Jacobus Cornelius Kapteyn (1851–1922) and his wife Cathe- rina Elisabeth Kalshoven (1855–1945). They had married in 1879, after Kapteyn had taken up his professorship in astronomy and theoretical mechanics at the Uni- versity of Groningen, to which he had been appointed in 1878. Henriette had an older sister Jacoba Cornelia, born in 1880, and a younger brother Gerrit Jacobus, born in 1883. In historical notes about Kapteyn, whenever this biography is mentioned, the name of the author is almost invariably written as Henrietta Hertzsprung-Kapteyn,

1Aan mijne moeder, zonder wie dit leven nooit zoo volkomen had kunnen zijn, Dedication in her biography of her father J.C. Kapteyn.

© Springer International Publishing Switzerland 2015 639 P.C. van der Kruit, Jacobus Cornelius Kapteyn, Astrophysics and Space Science Library 416, DOI 10.1007/978-3-319-10876-6 640 B Henriette Hertzsprung-Kapteyn’s Biography

Fig. B.1 The title page of the biography by Henriette Hertzsprung-Kapteyn (left), and a photograph reproduced from that volume showing the author with her father

so the question arises whether the last letter should be an ‘a’ or an ‘e’. The cover of the book only has her first initial ‘H’. On the other hand, a number of genealogies of the Kapteyn and Kalshoven families can be found on the WWW that all spell her name Henriette [2]. The City of Groningen provides electronic, public access to its archives, including the birth register for the period from 1811 onward (up to one hundred years prior to the queries). These archives, named Alle Groningers [3], contain the birth certificate of Henriette Kapteyn (see Figure B.2). Clearly her name is spelled with an ‘e’ at the end. Note also that no dieresis or umlaut is used over the second ‘e’. The same is true for the first‘e’ in Mariette. Henriette studied in Groningen and in Amsterdam and obtained the ‘Candidaats’ degree (this is the title obtained more or less halfway through academic studies, roughly comparable to what nowadays would be the Bachelors degree) in law and an ‘MO’ degree in English (see Inge de Wilde: Nieuwe Deelgenoten in de Wetenschap: Vrouwelijke studenten en docenten aan de Rijksuniversiteit Groningen 1871–1919 [4]). MO stands for Middelbaar Onderwijs (secondary education) and the certificate qualified for teaching at gymnasia and high schools (HBS; see page 62). Henriette Kapteyn married the Danish astronomer Ejnar Hertzsprung (1873–1967) on May 16, 1913. The marriage certificate of Ejnar Hertzsprung and Henriette Kapteyn is also available in the archives of the city of Groningen (see Figures B.3 and B.4). Here her first name is also spelled Henriette. B.2 Ejnar Hertzsprung and First Marriage 641

Fig. B.2 Reproduction of Henriette Kapteyn’s birth certiﬁcate from the archives of the city of Groningen (From Alle Groningers [5])

A similar issue is whether the last name should be spelled Kapteyn or Kapteijn. J.C. Kapteyn always used the ‘y’ and his and her name are also spelled in that manner in the biography that Henriette wrote. This seems sufficient reason to adopt it. It is also spelled Kapteyn in the birth certificate of Henriette (see Figure B.2). However, in the marriage certificate in Figures B.3 and B.4 the family name of Henriette herself, of her father and her uncle Frederik Willem Hendrik Kapteyn (1853–1920), who acted as an official witness, was spelled Kapteijn. Note that all signatures do not have dots over the ‘y’ which would be required to make it an ‘ij’. The site Alle Groningers has more official documents of Kapteyn and his relatives, but most can be found by searching for the name ‘Kapteijn’.

B.2 Ejnar Hertzsprung and First Marriage

Hertzsprung, who was senior to Henriette by eight years, was trained as a chemical engineer in Copenhagen and obtained his degree in 1898. A biography of him by Dieter B. Hermann was published in German under the title Ejnar Hertzsprung, 642 B Henriette Hertzsprung-Kapteyn’s Biography

Fig. B.3 Marriage certiﬁcate of Ejnar Hertzsprung and Henriette Kapteyn on May 16, 1913. This section shows the top part. The scribbling in the left-hand margin is an entry to the effect that the marriage was dissolved by divorce in 1937 (From Alle Groningers [7])

Pionier der Sternforschung [6], and I have taken some details from this below. Hertzsprung worked in St Petersburg, but in 1901 he went to Leipzig University to study photo-chemistry. He returned to Denmark in 1902 and worked at Copen- hagen University Observatory and at the (private) Urania Observatory. In 1909 he was appointed by Karl Schwarzschild at the Astrophysikalisches Observatorium in Potsdam. Before that, Schwarzschild had been director of the Sternwarte Gottin-¨ gen and moved to Potsdam to manage the local Astrophysikalisches Observato- rium in 1909. Schwarzschild is best known for his solution of Albert Einstein’s ﬁeld equations of general relativity of a spherically symmetric case, leading to the Schwarzschild radius, which is the size of the event horizon of a black hole. In 1919 Hertzsprung went to Leiden Observatory and became its director in 1937. He retired in 1946. His greatest contribution is his work on the classiﬁcation system for stars according to spectral type, stage in their development and luminosity. This resulted in the Hertzsprung–Russell diagram, which has been instrumental in understanding stellar evolution. While Hertzsprung worked in Potsdam, Schwarzschild recommended him to Kapteyn, who decided to introduce him to Hale and bring him along on one of his visits to Pasadena. In 1911 Hertzsprung paid a lengthy visit to Groningen and B.2 Ejnar Hertzsprung and First Marriage 643

Fig. B.4 Marriage certiﬁcate of Ejnar Hertzsprung and Henriette Kapteyn on May 16, 1913. This section shows the bottom part. The signatures below those of Ejnar and Henriette and in the middle are those of the witnesses Gerardus Heymans (professor of psychology and philosophy), Carl Vollgraff (professor of Greek), uncle Frederik Kapteyn and brother-in-law Willem Cornelis Noor- denbos (From Alle Groningers)

Kapteyn. Klaas van Berkel notes in the Legacy (page 161): ‘In Groningen, Hertz- sprung however not only got to know Kapteyn much better, but also his daughter Henrietta [should be Henriette], and when he left for the US in June 1912 the two of them were engaged.’ Henriette and Ejnar had one child, a daughter Rigel Hertzsprung (1916–1993), named after the bright star (see Fig. 16.14). The marriage was not a happy one and they divorced formally on January 19, 1937. They had separated long before that date. In his biography of Hertzsprung, Herrmann quoted from a in a letter of Hertzsprung to his sister of ‘May 23, 1923, a few months before his ﬁftieth birthday’, that ‘he and Hetty have decided to separate and to dissolve their ten year old marriage. Daughter Rigel was 7 years ofageatthattime.’Many persons, including Adriaan Blaauw, who had studied with Hertzsprung, have conﬁrmed the widespread opinion that Hertzsprung was a workaholic with little interest in social and other non-professional matters. Klaas van Berkel wrote in the Legacy: 644 B Henriette Hertzsprung-Kapteyn’s Biography

Fig. B.5 Tombstone on the graves of Henriette Kapteyn and her second husband Joost Hudig on the Begraafplaats Leeuwerenk, Oude Diedenweg 64, 6704 AD Wageningen (From Online begraafplaatsen [9])

‘It is unclear however how quickly Kapteyn came to realize just how un-social Hertzsprung was. If we have to believe Luyten, he should have known this before the couple was married. ‘For three or four months [after his departure for the US] she [Henriette Kapteyn] never heard a word from Hertzsprung, and ﬁnally Kapteyn wrote to the director of Mount Wilson Observatory about it. Eventually Hertzsprung’s ﬁancee received a postcard from him on which he wrote: ‘So sorry not to have written before, but the skies here are so beautiful, and, you see, where the stars are, there I’m happy.’ ‘ (Luyten, My First 72 Years [8].) Since Kapteyn had traveled to the US. for his yearly stay at Mount Wilson together with Hertzsprung and must have returned in September or early October, this story, if true (and Luyten says he had heard it from Henriette Kapteyn herself), implies that only after returning from the US. Kapteyn was informed about Hertzsprung’s lack of attention.’ Willem Jacob Luyten (1899–1995) had obtained his PhD under Hertzsprung in Lei- den in 1921. B.4 The Biography and Hale 645 B.3 Joost Hudig and Second Marriage

A few months after the formal divorce, Henriette married Joost Hudig (1880–1967), in London on April 17, 1937. Hudig was a chemical engineer and specialized in pedology (soil study). He had earlier married Sophia Alida Hudig in Rotterdam in 1905, where both were born (Sophia in 1880; although they shared the family name Hudig, they were not close relatives). Shortly after that they moved to Groningen, where two daughters were born, Johanna Clementina Johanna in 1907, and Johanna Elisabeth in 1909. The elder daughter studied law and became the first female judge in the Netherlands. The site Alle Groningers only contains births up to 100 years before the time of consultation, so there may have been more children after 1910. On public record are also the deaths of son Ferrand Whaleij in 1911 (3 days old) and son Joost in 1920 (7 years old). Sophia Alida died in 1924 at the age of 44 and Hudig had been a widower since then. Joost Hudig worked at the ‘Rijkslandbouwproefstation’ (State Agricultural Lab- oratory) in Groningen, of which he also became director. In 1929 he was appointed professor of chemistry and the science of fertilization at what is now the Agricultural University of Wageningen, where he worked until his retirement in 1949. Hudig features in Henriette’s book, in Chapter 15. According to her descriptions, Kapteyn and he were neighbors and Hudig acted as secretary to the scientific chapter of the ‘Natuurkundig Genootschap’ (the current Royal Natural Sciences Society), when Kapteyn was its chair (see page 282). Indeed Hudig moved to the address Ooster- haven ZZ 12 around 1908; Kapteyn lived at number 16a between 1906 and 1910. Henriette was 25 when the Hudigs moved there and she probably no longer lived then with her parents. Henriette and her second husband were buried in Wageningen. The tombstone is shown in Figure B.5. Note that here there is a dieresis in Henriette’s first two names.

B.4 The Biography and Hale

In the Preface I presented the note written by Willem de Sitter requesting help in the preparation of a biography that he and Johan Huizinga we preparing to write. I do not know who of the colleagues responded, but George Hale most certainly did. On March 21, 1927, Hale wrote to Huizinga offering his help and sending a list of letters sent by Kapteyn to himself, Walter Adams and Frederick Seares, with the numbers of pages and the ﬁrst and the last phrases, prepared by his secretary. In the same letter he mentioned that ‘Mrs Hertzsprung’ had also contacted him. Huizinga acknowledged the receipt of this letter on April 2, 1927. The ensuing correspondence (see als Petra van der Heijden in the Legacy [10]) between Hale and Kapteyn’s wife and daughter tells an interesting story. Well before that date, on October 28, 1925, Henriette Hertzsprung-Kapteyn had written to Hale asking him for ‘a few lines about reminiscences of him and about his life at Mt. Wilson’. She wrote this letter from the address Oude Amersfoortsche 646 B Henriette Hertzsprung-Kapteyn’s Biography

Weg 66 in Hilversum. She had moved to Hilversum after her separation from Hertz- sprung, together with her daughter Rigel, presumably to be near her mother. Ap- parently the latter had moved into a house nearby (at no 29 in the same street). She referred to delays ‘because of my altered conditions’ and also mentions examina- tions she had been preparing for. Further she noted that she advanced ‘but slowly, as I have my child and my household all to myself, the child being a very curious and original specimen of humanity with difficult, but promising properties’. She signed the letter ‘Hetty Hertzsprung-Kapteyn’. Rigel (1916–1993) had suffered mi- nor brain damage due to a forceps delivery. She first lived with her mother, but later with her father when he moved to Denmark. She seemed to have had affairs with men, which gave rise to some tensions about her ability to arrange her financial affairs in the family relations, especially with her aunt Jacoba Noordenbos (Kapteyn’s oldest daughter), until she married a Danish waiter with the name Thorning. She died in an accident with a bus at a bus-stop. [11] Hale replied on January 20, 1926, apologizing for his delayed reaction and in- quiring into the connection between the biography she was writing and the one by professor de Sitter. Henriette answered on February 11, 1926, again from her address in Hilversum, saying that she had the ‘view to write my own little book for his family and friends. Their [she means de Sitter and Huizinga] work will be a standard work of great value no doubt, but mine will be a simple story of his personal life with as much of his science in it, as I can bring in with my ignorance of astronomy’. And again she asked for a contribution with regard to her father’s work at Mount Wilson and Hale’s personal memories of him. On August 13, 1926, Hale wrote that he had found himself ‘whol[l]y unable to write anything suitable’ and apologized for that. He did include a few remarks (that Henriette eventually used in the biography), however, and told her to ‘feel entirely free to omit it from the book if it is late or in your eyes unsatisfactory’. Henriette responded on October 19, 1926, explaining that her work on the biography had been delayed ‘as my house has been repaired’ and also mentioned that her mother was in excellent health. ‘We do enjoy living so near to each other’. She also mentioned that Huizinga had been visiting her mother and herself, and conveyed her envy of him for having visited Pasadena, where she had never been and which was to her, ‘child of my parents, an almost sacred place’. There was no reference to Huizinga’s progress with the biography. Henriette’s biography, obviously, is in Dutch. She wrote to Hale again on August 28, 1929 (after the book had been published), saying that she aimed to publish it in America in English translation and that she had consulted Huizinga and a professor Barnow of Columbia University. This is a misspelling; it must have been Adriaan J. Barnouw (1877–1968), Dutch by birth and a professor of Dutch language and literature on the Queen Wilhelmina Chair, since 1919. Barnouw is particularly known for his translations into English of some Dutch medieval legends, fables and poems. Henriette had hoped to translate her book herself ‘as many astronomers asked me to’, but found it impossible to make it ‘fit for an American public’. Note that this was in spite, or maybe because, of the fact that she had studied English. She asked Hale for help to find a publisher and inquired into the possibility of the book coming B.5 Paul’s Translation 647 out as a ‘separate publication of the Mt. Wilson Observatory’. Hale informed her that he had received a copy of the book and said that he had been able to make out enough of it to ‘get the chief features of your narrative’, but that ‘all matters on publication were decided on by the President of the [Carnegie] Institution’ and that he had written him about it. Hale reported back that funds were insufficient, but that he had taken things up with the Publications Committee. On March 19, 1930, Hale wrote that the Carnegie Institution was unable to find the financial means but that it would make an effort to find an American publisher. Henriette acknowledged this on May 7, 1930. However, on July 24, 1930 the editor of the Carnegie Institution (Frank F. Burker) wrote to Hale that he had been unsuccessful in finding a publisher, which was reported to Henriette Hertzsprung-Kapteyn on August 4, 1930. The efforts to publish an English version of the HHK biography had proved to be of no avail.

B.5 Paul’s Translation

Much more recently the biography was still translated, by E. Robert Paul, first as a contribution to the journal Space Science Reviews [12], later as a book The Life and Works of J.C. Kapteyn by Henriette Hertzsprung-Kapteyn: An Annotated Transla- tion with Preface and Introduction by E. Robert Paul [13]. It also contains a list of publications about Kapteyn and notes about astronomy in his time. E.R. Paul was definitely an authority on the subject of Kapteyn and astronomy of his days and published a number of authoritative papers and a scholarly book on the subject (see the Preface, page viii). The translation of Henriette Hertzsprung-Kapteyn’s biography has been seriously criticized. I reproduce the following paragraphs from Appendix B by K. van Berkel and P.C. van der Kruit in the Legacy: ‘In this volume and in almost any other study of Kapteyn, reference is made to the biography by his daughter J.C. Kapteyn, Zijn Leven en Werken, published in 1928. This only biography of Kapteyn has been translated into English(andannotated)byE.RobertPaul.[...]VariousDutch-speaking participants, present at the Symposium, commented on the sometimes misleading translations. Prof. Adriaan Blaauw informs us as follows: ‘In August 1993 I learned by chance from one of the associates of Kluwer Academic Publishers, Dr K. (not an astronomer), about Robert Paul’s translation. Publication was in an advanced state, the book was just about to be printed. Dr. K. agreed to slightly delay the printing in order for me to have an opportunity to acquaint myself with the contents. I was impressed by Paul’s sympathetic effort to make Mrs Hertzsprung-Kapteyn’s work accessible to the English speaking community and his extensive annotations about the personali- ties – astronomers and university colleagues – occurring in her narratives. However, I was startled by the poor quality of the translation. 648 B Henriette Hertzsprung-Kapteyn’s Biography

I learned that Robert Paul had done this himself, and it was obvious that he had grossly underestimated the pitfalls of the Dutch language. On August 26, I sent Paul by rapid mail 60 proof pages marked with my corrections. My inspection – done under heavy pressure of other work – had been far from exhaustive. In my accompanying letter to Paul I wrote: ‘[...]TheDutchlanguage,asitisusedbysomeauthors,canbeofrather complicated structure [...] andthereby sometimes may be misleading to foreigners. Mrs Hertzsprung’s writing [...]isnoexception.Therearecases (as you will note from my corrections), where the imperfect translation then leads to just the opposite from what she meant to say. There are also among my corrections some due to the fact that a Dutch word can sometimes have more than one quite different meanings, and the alternative would have been the correct one. [...] My suggestions for improvements were acknowledged by Dr. K. on Au- gust 31. It was only after publication of the book that, from the com- plimentary copies I received, I could judge to what extent they had been followed up. It seemed to me that this was the case only for those, that did not require drastic surgery of the page-proofs. So, unfortunately, the book still contains many traces of the imperfect translation. Alas, Robert Paul died on October 12, 1994, of cancer, at the young age of 51, a little more than a year only after the publication of the book. An obituary, written by Steven J. Dick, appeared in the Bull. Am. Astron. Soc. 26, 1606 (1994). Isn’t it likely, that Paul, already suffering from his fatal disease during the last stages of the publication of the book, so shortly before he passed away, did not have the strength anymore to thoroughly revise the text? Wondering about the origin of the present, unsatisfactory situation, it has always been incomprehensible for me that Kluwer accepted the text as it was. One wonders whether Kluwer’s editorial advisory committee for the series Space Science Reviews had a really serious look at the manuscript. I took the matter up again in February 1996 with Dr K.’s successor at Kluwer, Dr de G., and sent him two sets of copies of the pages of the manuscript – corrected and not corrected – in the hope that Kluwer would makeanefforttoremedythesituation.Thishasnotbeensuccessful.’[...] The appendix in the Legacy contains more details and examples of poor quality translations, but I refrain from repeating this her, except for the final paragraph: ‘There is no doubt that E. Robert Paul has done scientific inquiry a great service with his perceptive studies of the history of (statistical) astronomy in Kapteyn’s days. However, it is clear from these examples that his translation of Henriette Hertzsprung-Kapteyn’s biography is untrustworthy and useless for scholarly purposes. Those who are able to read Dutch do not need his translation, and those who for one reason or another would like to use it after all, will still have to consult the original to check whether Paul provided the correct translation. It would be useless to try and improve this translation, since the work would have to be redone from beginning B.5 Paul’s Translation 649

to end. Perhaps the publication of the translation made by Peter van de Kamp, which never saw the light of day because Paul’s translation was forthcoming, would oﬀer a way out. But the best solution would be to have someone write a new and critical biography of Kapteyn, based not only on Henriette Hertzsprung-Kapteyn’s book, but also on the more recent literature concerning the life and work of Kapteyn, including the historical contributions to this volume.’ In a book review of Paul’s translation, Derek Jones [14]wrote:‘I am not a scholar of Dutch and cannot comment on the accuracy of the translation, but the resulting English is diﬃcult to read because of the strange usage and vocabulary. [Paul’s translation] attempts to convey both the spirit and intent of the original biography and attempts to preserve the many Dutch idiomatic expressions.’ Maybe this was not such a good idea after all. I have produced a revised English translation of the biography by Henriette Hertzsprung-Kapteyn and posted it electronically on the Website I maintain on Kapteyn [15]. Unlike Paul, I did not attempt to rewrite the sentences but tried to stay as close to the original text as possible. I have used major parts of this translation in this book, where I felt the texts were important to illustrate certain aspects of Kapteyn’s private and non-professional life. 650 B Henriette Hertzsprung-Kapteyn’s Biography

Fig. B.6 Kapteyn at Mount Wilson in 1908 (Photograph Kapteyn Astronomical Institute) Appendix C Cornelis Easton: Personal Memories of J.C. Kapteyn

His straw hat had lost its original cleanness long ago; no umbrella in spite of the rain –‘I am not allowed umbrellas anymore’, he said jokingly, ’I lose them all the time’–. Cornelis Easton.1

Not long after Kapteyn’s death a tribute was published in two installments in the Dutch journal Hemel & Dampkring (Sky & Atmosphere), the magazine of the Dutch association of amateur astronomers and meteorologists, in August and September 1922. In the Kapteyn Room at the Kapteyn Astronomical Institute there is a copy of a reprint of the two parts that were presented by the author to Kapteyn’s widow C.E. (Elise) Kapteyn–Kalshoven. Three of the four illustrations in the publication have been reproduced in this appendix; the fourth has been reproduced on page 350. Two of these ﬁgures are drawings of Kapteyn by Easton himself. The author, Cornelis Easton (1864–1929) (see Fig. 11.12), a Dutchman in spite of his name, was a prominent journalist and newspaper editor. He had had no formal training in astronomy, yet conducted original research in that ﬁeld and in climatol- ogy and published a number of papers in professional journals, some of them in conjunction with Kapteyn. In recognition of his contributions, he received an honorary doctorate from the University of Groningen in 1903 with Kapteyn as his ‘pro- motor’. At the time Easton wrote the article, he was editor-in-chief of the newspaper De Dordrechtsche Courant.

1In the article discussed in this appendix.

© Springer International Publishing Switzerland 2015 651 P.C. van der Kruit, Jacobus Cornelius Kapteyn, Astrophysics and Space Science Library 416, DOI 10.1007/978-3-319-10876-6 652 C Cornelis Easton: Personal Memories of J.C. Kapteyn

The full text of the original article in my English translation is available at my Kapteyn-website [1]. In this appendix I reproduce only the parts that concern the person of Kapteyn. It starts with a dedication.

To be the Eckermann of this Goethe! The Forster of this Dickens!. . .

Johann Peter Eckermann (1792–1854) served for a number of years as Goethe’s personal secretary and after Goethe’s death published a book Conversations with Goethe.. He was also involved in preparing Goethe’s works for posthumous publication. John Forster (1812–1876) is well-known for his biography Life of Charles Dickens. He is said to have been in the possession of the original manuscripts of Dickens’s novels, which he later bequeathed to the South Kensington Museum. ‘On a sunny afternoon in the year 1894, now already almost thirty years ago, I found myself in front of prof. Kapteyn, who had come to my hometown as a external examiner for the final high-school exams. I was met in the bare waiting room in the Gymnasium of Dordrecht by a tall, lean man who was looking remarkably young for his 43 years. My first impression of the man was: How tall he is! I have addressed the question of Kapteyn’s height on page 56. He seemed to be looking over the heads of almost all his peers and that impression was strengthened by his upright head on a long neck. Already then his eyelids where long and hanging low, which could give the impression that he not only from high up, but also somewhat disparagingly looked down upon the world. His hair and mustache were of a light red color. A handsome face, by the way, with a delicate nose and busy lips, a face that seemed tight from inner emotional tensions. Compared to professor van de Sande Bakhuyzen with his friendly, charm- ing manners (that this good man has conserved up to the present day) I at first found the young Groningen professor not really forthcoming. There were two reasons for that, as I only later understood. Kapteyn was, except when science was concerned, extremely stringent, and therefore cautious for interference from interested outsiders. He had much appreciation for the work of ‘amateurs’ in astronomy, such as Franklin Adams, but he then had to be convinced that their work was sufficiently significant to spend time on.’ Easton refers here to John Franklin-Adams (1843–1912), a British amateur astronomer. He was famous for his ‘Franklin-Adams plates’, which constituted a photographic atlas of the night sky. To devote his life to the most extensive and complicated of all astronomical problems: the structure of the Universe –that grand resolve must have been developing in his thinking in his junior years when he resolved to dedicate himself to astronomy. ‘Le long espoir et les vastes pensées’. are being born at that age. [. . . ]’ C Cornelis Easton: Personal Memories of J.C. Kapteyn 653

In full the quote is ‘Quittez le long espoir et les vastes pensees,´ – Tout cela ne convient qu’a` nous’ (Long-growing hope, and lofty plan, Leave thou to us, to whom such things belong [2]) It is a citation from a poem by Jean de la Fontaine (1621–1695) –Fables (1668–1694), Livre onzieme,` VIII, Le vieillard et les trois jeunes hommes (The old man and the three young ones) – about an old man who plants trees for future generations. ‘After our first meeting Kapteyn quickly paid me a visit in return. My guest was a heavy smoker and was fond of a glass of wine – later he would give up both of these almost completely, for the benefit of his eyes. Not out of principle. He hated ‘Prinzipienreiterei’ (harping on about principles), and what little he needed for satisfaction, he did enjoy the less high-minded joys of life. ‘One of my sisters’, he once said, ‘has had her molars removed without anesthesia. I would never do that. One has to accept the pain that must be suffered and I admire that, but why not avoid unnecessary pain?’ [...] The following years our paths did not cross, and only around the turn of the century I was in a position to visit Kapteyn in Groningen. At that time they lived in the Heerestraat, simple but spacious. It was a pleasure to stay with that family, also later in the remarkable and cozy upper floor on the Ossenmarkt. Immediately after arrival the guest was put at ease, with so much pleasant business and care as if one had just arrived from a train trip from at least St. Petersburg. The professor’s soft calmness was happily complemented by the busily moving around of his wife, hopping around it seemed like a bird; both were cordial in their own manner. With them were two daughters and a son. It was one of those households that would have amused Dickens enormously. Dickens, by the way, was present like a good friend in their house; during their first years of marriage husband and wife had read out aloud to each other the complete set of 20 volumes, and a bust of the unforgettable story teller stood in Mrs Kapteyn’s bookcase. Moving detail: during his fatal illness, when Kapteyn had to rest most of the time, only a few weeks before his death he was visited by his friend Charles Edward St. John in Amsterdam. Talking with the ill man was not very well possible, but he did read out to him, at his request from Dickens. . . .’ Charles Edward St. John (1857–1935) was an astronomer from Mount Wilson Observatory. ‘The man of whom in England recently it was claimed that he had done the most important discovery in the area of stellar astronomy since the time of the Herschels, showed no sign of proud self-consciousness or professorial dignity, when on an evening in June in the year 1906 I picked him up at the Meuse Railway station in Rotterdam. He looked extra unassuming. His straw hat had seen its original cleanness long ago; no umbrella in spite of the rain – ‘I do not get any umbrella’s anymore, he said jokingly, I loose them all the time’ – and we moved slowly, but not unnoticed, through the crowd to our house.’ 654 C Cornelis Easton: Personal Memories of J.C. Kapteyn

Fig. C.1 Illustration accompanying the article of C. Easton in Hemel & Damp- kring. This is a drawing of Kapteyn made by Easton himself. The year is ‘about 1890’ and Kapteyn must have been about 40 years of age

The Meuse railway station in Rotterdam is no longer in use. ‘There was only one thing that was more pleasant than staying with the Kapteyns; to have Kapteyn staying with you. This extraordinary man was able to neutralize, through his not particularly exuberant, but fully natural good spirits, the oppressing influence of a modern street in Rotterdam under a dark, wet sky in the summer. At home, during a cold dinner, the subject of conversation turned to life in Groningen.’ Easton here probably means a dinner that consisted of cold dishes, and not a cooked meal that had turned cold. ‘Rob’ [Kapteyn’s son Gerrit Jacobus] had left home. ‘A boy with many talents and a good brain (said his father), but he has the characteristic habit, inherited from his ancestors, to do exactly what he wants to. Well, I do not give up hope; we were with ten brothers and five sisters and we all ended up well.’ ‘But maybe it was ornithology to which – second to astronomy – he felt attracted most. Had astronomy left him more spare time he would have, it seems to me, been inclined to spend each free afternoon lying on his stomach somewhere in the fields or hiding in the reeds watching birds with a copy of Jac. Thijsse’s book in his pocket.’ C Cornelis Easton: Personal Memories of J.C. Kapteyn 655

Jacobus Pieter Thijsse (1864–1945) was a botanist, who wrote a little book Het Vogeljaar, published in 1903, which became the most popular book on birds in the Dutch language and was reprinted many times. ‘He knew a lot about that, and whoever has tried to tell a few dozen or even one dozen Dutch songbirds apart, only by listening to their songs, will realize that it must have taken much dedication and diligence for one who had so few hours, even minutes, to spare, to have gone that far. I remember a walk with him and with our Jan and Titia in the woods near Bloemendaal. What a delightful companion he was for children! ‘Children’, he had comforted them that Sunday morning, when he had noticed two pairs of eyes looking disappointingly at a wet, gray sky filled with clouds, ‘children, the gardener of my uncle always said: if there is only one little patch of sky big enough to cut a pair of trousers out of, then it will become nice weather!’ – And indeed, the weather turned nice. In his manner we wandered through alleys passing high beeches and he was the first among us who noticed an estrildid finch in the distance sitting on a fence. And we heard the estrildid finches, and chiffchaffs (who ricochet pebble- stones against each other) and the garden warbler, who goes on and on, and the willow warbler, about which Thijsse writes so emotionally, and then we laughed about this, as wise city dwellers, but deep in our hearts we found that lingering dying out of the soft song of this bird very moving. And we came home merry, like large and small children (the great Kapteyn included) that had relished a rare free day. [...] The next days of his stay in Rotterdam he served again as external examiner for the final exams of the grammar school. When he came back home we were treated of course with the corresponding jokes. One pupil had translated ‘ici-bas’ as ‘here stocking’, somebody else translated the sentence ‘Platon et Socrate sont deux philosophes’ as: ‘One great philosopher and one great philosopher makes two great philosophers’. (I don’t doubt the authenticity of this, but also cannot resist to suppose it was made up at home using a dictionary.) ‘How much money (another question at the exams) does one need to invest in order to pay the tuition of 1000 Guilders per year for four years of studies of his son, who now is four years old? One candidate found an answer of 87 Guilders and 42 cents; but there also was another candidate who found such an enormous number that he had to write diagonally on his piece of paper in order to fit it on one line.’ When the laughing had died away he started to tell the most hilarious stories, such as how he once was staying somewhere as a guest, had opened the double doors of his bedroom to get some fresh air on the balcony, only to find that by holding on to the door handle he could barely avoid falling down three stories, as there was no floor to the balcony!. . . He was the most pleasant and entertaining companion when he was among good friends. He and my wife would roar with laughter about little things. Once she came to bring him a cup of coffee in the morning: the tall man – it was summer and hot – was sitting in the open window, 656 C Cornelis Easton: Personal Memories of J.C. Kapteyn

staring over the landscape behind him, softly humming or softly talking to himself, deeply absorbed in thought, probably about his luminosity function or selective absorption in space. On the sound of the door opening he turned to look inside but heavily bumped his illustrious head. While rubbing that part of his body he made such a strange face that his hostess burst into laughter so much that she had to put the cup down so as not to spill the coffee, and while he shouted ‘So, what is there to laugh about’ he laughed himself along with her until he had tears in his eyes. Sometimes he told about his youth. Of the prowess of one of his brothers, who was posing as ‘little Mercury’ on the ridge of the house’s roof, standing on one leg, while his father looked up and was not able to move being filled with fear. – Or: that he on an occasion had sat down on the hanging frame that house painters were using, upon which the frame started to come down in small steps – how he escaped from it he did not remember. Or how he and one of his brothers in the times before the ‘Rover safety’ exultantly cycled into the hometown Barneveld; there nobody had seen bicycles and the populace all gathered in great numbers to see them so that the two cyclists fell from their two-wheelers ‘like ripe pears’.’ The ‘Rover safety’ is the model for our modern bicycle with a diamond shaped frame and two wheels in the same line, the rear one driven by a chain. ‘Kapteyn was not a born speaker. He never had done any training in the art of elocution – he would not hear of it – his performance was simple and far from impressive, his voice somewhat high-pitched and nasal. Also he was not able to, as Lorentz could in an unsurpassed way, drive his presentation so in your brains, so to speak, that for a moment you understand the most difficult things, that is to say seem to understand – as long as the impression lasted. Kapteyn’s mind was in the other hand so completely clear and logical, his choice of wording so excellent, his gestures so simple and still expressive that he needs to be counted among the best in explaining abstract matter. It was most difficult for him, who lived with his subjects from early in the morning until late at night, to judge the extent the background knowledge and ability to grasp things among his listeners; but even those that did not fully comprehend it all, still left for home with a ‘profit’. His mind was preoccupied more with important things than caring for his appearance, and whoever would see him en neglig´ e´ [in casual dress as if at home with no guests around] could take a photograph of him as seen in the previous issue of this journal, but that does not mean he did not care about his appearance. Whenever he felt it was worth the trouble to dress with care, he would tend to prefer the modern over the old-fashioned in his suits. His tall figure made it easy to dress well. When he wore his professors’ gown he even could look like a dignified professor. Presenting himself officially he did through his manners, just as he would be a worldly person on other occasions. Through his broad education, his knowledge of languages, his fine sense and tact, being worldly was natural and easy for C Cornelis Easton: Personal Memories of J.C. Kapteyn 657

him – although it was not part of his character to develop relationships out of vanity or as a “bridge’, a means to go where he wanted to be. In those case he traveled the ‘royal’ road; he accomplished what he wanted simply through his own extraordinary and undeniable merits. Was he indifferent to recognition? Absolutely not. I think that in recent years, and shortly after his death, there has been too much reference to his modesty. One should not think that he drifted over the vanities of the world with downy wings of angels in childish naivety. He was extremely well aware of the social orders and used these in practical manners whenever he could make use of them –in the first place to promote his work. In scientific matters he was never short of funds for his research in this ungenerous rather than free-handed society of ours and what he lacked in guilders he knew how to supplement in dollars. That he did not aspire personal gain, nor honors, goes without saying: people do not regard such altruism with scientists and artists as very normal, but take their own self-interest for granted. Of course the honors did come his way, but only in later years. They pleased him enormously, and not just because it reflected upon those around him; he was too sensitive a person to be insensitive to wide appreciation. Vanity in the petty sense of the word, was foreign to him; others, not himself, were annoyed that the Netherlands awarded him ‘the Lion’officiallyforhishavingbeen...... ateacherfor25years;thefactthat the state was not represented at his 40-th anniversary as a professor; that this great Dutchman, had he been born in England undoubtedly would have been ‘Lord Kapteyn’ long before his death, at his retirement was honored(!) with just a little more than an average Royal distinction in a second rate order. [. . . ]’ The ‘lion’ here refers to the Royal distinction of Knight in the Order of the Dutch Lion. In the last sentence, Easton refers to Kapteyn’s Royal distinction as Comman- der in the Order of Oranje-Nassau, which is nowadays seen as a significantly higher distinction than average. Even the slightly less prestigious Knight in the Order of the Dutch Lion is nowadays well above average. ‘Therefore he often made the impression of an almost funny calmness, with a bit of indifference for the minor things in life. It sounds a bit comical when we see him described in an American newspaper after a lecture he had given somewhere in California as ‘a quiet, modest, almost bashful man’. Maybe this journalist on the other side of the Big Pond thought that an ordinary scientist had to be a sort of stubborn idiot and an extraordinary scientist, a noisy boaster. He did make a compliment on the stranger’s English: ‘Like nearly all educated foreigners who essay to speak the English language, he does so with an accent (well! listen to the American English! – E.), but with a pureness of idiom and diction, which makes of it really classical English. His literary productions in English are marvels in their strong, vigorous simplicity’. – Indeed, he did know how to write in other languages, English in particular, as easily as he spoke them; also in this area he displayed his versatility. [...] 658 C Cornelis Easton: Personal Memories of J.C. Kapteyn

Fig. C.2 Illustration accompanying the article of C. Eas- ton in Hemel & Dampkring. It is a drawing of Kapteyn by Easton in 1920 (see text)

A few years before the war, when I had sent him a set of photographs that was published as a Photographic Chart of the Milky Way, he wrote to me: ‘I have put this map on the wall next to my work table, but for the moment I feel that the profound implication works depressing. While working with papers I sometimes feel a certain satisfaction and especially hope – the appearance of the details that all need to be explained, subsequently reduces this to a proper feeling of insignificance.’ ‘For that ‘certain satisfaction’ there were very good reasons. Only few researchers are blessed with the opportunity to see the result of their labors grow in their hands into a magnificent edifice, aere perennius.Hesawit and it must have given him the greatest and purest joy and ‘intellectual’ experience.’ Easton refers to a paper he published in the Astrophysical Journal in 1913, A photographic chart of the Milky way and the spiral theory of the Galactic System [3], see Fig. 11.13. The quotation is ‘Exegi monumentum aere perennius’; I have erected a monument more lasting than bronze. It is from Horace (Quintus Horatius Flaccus; 65BC–8BC). ‘Since he never wasted time or energy and in later years more and more became aware of his health, he made everything subservient to his C Cornelis Easton: Personal Memories of J.C. Kapteyn 659

Fig. C.3 Illustration accompanying the article of C. Easton in Hemel & Dampkring. It is a photograph of Kapteyn at the age of 70

scientific mission. He did have an interest in the world around him, but he intentionally did not actively participate in social activities. He never was a member of a city council; he was, if I am right, not a member of the board of a society or club and he did not participate in conferences on a general subject.’ This is not correct, since Kapteyn was a very active member of the board of the ‘Natuurkundig Genootschap’, see page 276. ‘He had become immune for ‘distraction’, which was enhanced by the fact that his wife took care of all other daily matters and he was not of a weak character. It even applied these to his social contacts; how cordial he may have been for his friends, the remark by ‘Larouchefoucauld’ was definitely applicable to him: ‘J’aime mes amis. . . . je n’ai pas des grandes inquiétudes en leur absence’.’ 660 C Cornelis Easton: Personal Memories of J.C. Kapteyn

François de la Rochefoucauld (1613–1680) was a French writer, well known for his collection of aphorisms. The full text is in English: ‘I love my friends, and I love them in such a way that I do not hesitate to sacrifice my interests to theirs, I support them, I patiently accept their bad moods and I do apologize for everything; I just do not show my affection all the time, and I have no great problems with their absence.’ ‘For one who was not very fond of attending meetings, he came relatively often to the sessions of the Astronomers Club that was founded in October 1918 at the initiative of Nijland. The drawing that I show here was made during one of those meetings in Utrecht. He was sitting more or less opposite from me, leaning somewhat backwards on his chair, but with his head straight up he had crossed his legs and as usual dangled one leg intensely on the knee of the other. He looked better then and took part in the discussions. His retirement was not very far away. The nice, (in an old-fashioned way) intimate house on the Ossenmarkt would have to be vacated.’ The following Easton presents is a footnote. That house deserves an article by itself. Strangers had to search for the entrance for a long time. There was a narrow passage next to the house between it and the next house and there one would find a small door that was almost never locked; next to it on a nameplate i.C. Kapteyn, rather than J.C. A dark winding staircase led to a beautiful spacious hall; the front living room was large also and the room in the back, that was furnished as a study – but in the evening everybody sat there, since K. did not work then to spare his eyes –, looked out over the gardens and the Nieuwe Kerk. Concerning his further plans: maybe still another trip to America next year, or a visit to Switzerland for a while; the dearest wish of Kapteyn and his wife though was their own house somewhere in ‘t Gooi, with five rooms or so,nomaid,butwitha dog...[...] It has not been given to him to spend the last part of his life quietly in the countryside. Still, the words of Wordsworth came true: And I should like my days to be Bound each to each by natural piety. He truly has been one of the high priests of natural science. Only death was able to extinguish in him the drive to uncover the truth, which is another form of religion. At the top of one of his rare popular articles he wrote this citation as epigraph, which describes his drive perfectly: If God held in His right hand all truth, and in his left nothing but the ever ardent desire for truth, even with the condition that I should err forever, and told me choose, I would bow down to his left, saying: ‘Oh, Father, give; pure truth can be but for Thee alone. William Wordsworth (1770–1850) was an English poet. I have not been able to find an article with this quote at the top; however, Kapteyn (1913a) has it at the end and I quote it from there. It is from Gotthold Ephraim Lessing (1729–1781). Appendix D Notes and References

If you don’t know where you’re going, you’ll wind up somewhere else. Yogi (Lawrence Peter) Berra (1925–present).

Below are further details on sources that were used or quoted in the text. These do not contain any remarks, further background or explanations, but are restricted to the bibliographic details of books, articles and other material, and provides, whenever possible, directions to websites where electronic versions can be found. The notes have been referred to in the text with the numbers between square brackets, starting at ‘1’ in each chapter or appendix. The ﬁrst set applies to the preface. Many astronomical journal papers that I refer to are available from the NASA Astronomy Data System ADS, which can be accessed at adsabs.harvard.edu in the USA or a number of mirror nodes on other continents. Whenever available, references to entries in ADS are included in these notes by their ADS designation.Soif for example the note refers to the paper A photographic chart of the Milky way and the spiral theory of the Galactic System by Cornelius Easton, published in 1913 in the Astrophysical Journal, 37, 105–118, the annotation [1913ApJ....37..105E] has been added. This means that this paper is listed in ADS and the full URL to access this paper is adsabs.harvard.edu/abs/1913ApJ....37..105E in the USA node, esoads.eso.org/abs/1913ApJ....37..105E in Europe, etc. For many, especially older publications, scanned versions of the papers are provided by ADS in .pdf or .gif formats, but in other (mostly recent) cases electronic subscriptions are required to download the full text from the journal or publisher’s site. Papers by Kapteyn himself or his close collaborators are in the text referred to by author and years of publication. These references are not given in this appendix, but appear in the listing of Kapteyn’s publications in Appendix A. Thus for example Kapteyn (1922a) is Kapteyn’s famous paper ‘First attempt at a theory of the

© Springer International Publishing Switzerland 2015 661 P.C. van der Kruit, Jacobus Cornelius Kapteyn, Astrophysics and Space Science Library 416, DOI 10.1007/978-3-319-10876-6 662 D Notes and References

Fig. D.1 Kapteyn in 1908 in the ‘Monastery’ (the residence of astronomers during their observing sessions) at Mount Wilson Observatory [4]

arrangement and motion of the Sidereal System’, published in the Astrophysical Journal, vol. 55, pages 302–328 (1922). For papers by Kapteyn for which no electronic versions are available on the Web, I provide scanned version on my Kapteyn homepage www.astro.rug.nl/JCKapteyn. References 663 References

[1] From The Progress of Science, the Scientiﬁc Monthly, June 1921. [2] The Observatory, vol. 48, 293–294 (1925). [1925Obs....48..293D] [3] She published it with P. Noordhoff in Groningen. The book is now part of the Digitale Bibliotheek voor de Nederlandse Letteren (Digital Library of Dutch Literature). See www.dbnl.org/tekst/hert042jcka01 01/, where versions in .pdf and .txt formats are provided. [4] Space Science Reviews, vol. 64, 1–92 (1993) (with a preface and introduction on pp. x-xix). [1993SSRv...64D...5P] [5] Kluwer (1993), ISBN 978-07-923-2603-8. [6] Journal for the History of Astronomy, 12, 77–94 (1981). [1981JHA....12...77P] [7] IAU Symp. 106, 25–42 (1985). [1985IAUS..106...25P] [8] Journal for the History of Astronomy, 17, 155–182 (1986). [1986JHA....17.. 155P] [9] Cambridge Univ. Press (1993), ISBN 0-5213-5363-7. [10] Kluwer (2000), ISBN 0-7923-6393-0. [11] See www.astro.rug.nl/JCKapteyn/HHKbiog.pdf. [12] University of Groningen (2008), ISBN 978-90-367-3353-3. [13] Princeton University Press (2000), ISBN-10 06-910-4918-1. [14] Centennial History of the Carnegie Institution of Washington: Volume 1, Cambridge University Press (2004), ISBN-13: 978-05-218-3078-2. [15] See the press release www.astro.rug.nl/ vdkruit/jea3/homepage/031209fwn nie uws.html. [16] See www.astro.rug.nl/∼vdkruit/jea3/homepage/address65.pdf. [17] See magazine.dutchancestrycoach.com/converting-dutch-historic-currencies. [18] Website at www.iisg.nl/hpw/calculate.php. [19] See www.astro.rug.nl/∼vdkruit/# Challenges symposium and www.elmerspaa rgaren-fotograﬁe.nl/. [20] New York, G.P. Putnam’s sons (1901), www.archive.org/details/starsstudyof univ00newciala; footnote on p.49.

Chapter 1. Growing up in Barneveld [1] The Observatory, 45, 261–265 (1922). [1922Obs....45..261.] [2] De Gids, Jaargang 86. 130–133, 1922. See www.dbnl.org/tekst/ gid00119 2201 01/ gid001192201 01 0081.php. [3] See www.clker.com/clipart-kaart-nederland-jan.html; online royalty free public domain clip art. [4] See www.barneveld.incijfers.nl/. [5] Nicolette M. Hijweege: Bekering in bevindelijk gereformeerde kring, PhD Thesis, University of Amsterdam (2004), ISBN 90-435-0995-7, dare.uva.nl/record/121886.; Saskia Reuzenkamp (ed.): Steeds gewoner, nooit gewoon, Sociaal en Cultureel Planbureau (2010), ISBN 978 90 377 0501 0, www.scp.nl/Publicaties/Alle publicaties/Publicaties 2010/Steeds gewoner no oit gewoon.; Fred van Lieburg (ed.): Refogeschiedenis in perspectief. 664 D Notes and References

Opstellen over de bevindelijke traditie. Groen (2007) ISBN 978 90 5829 780 8, www.dutchbiblebelt.org/fileadmin/uploads/2007Refogeschiedenis bundel.pdf. [6] See Waarom daar? by Jan Dirk Snel in ‘Refogeschiedenis’ (ed. F. van Lieburg, op. cit.). [7] See www.barneveld.nl/document.php?m=6&fileid=11445&f=56889951195fd cd171c14fc2108e5ffe&attachment=1&c=2724. [8] Website at www.biografischwoordenboekgelderland.nl/bio/6 Gerrit Jacobus Kapteyn. [9] Nr. 04.0394; beeldbank.ede.nl/atlantispubliek/default.aspx?modules=beeldban ken#media/410011/1 [10] Nr. 03.0553; beeldbank.ede.nl/atlantispubliek/default.aspx?modules=beeldban ken#media/498575/1. [11] Nr. 03.2280; beeldbank.ede.nl/atlantispubliek/default.aspx?modules=beeldba nken#media/464635/1. [12] See www.barneveld.nl/gemeentearchief/personen 3619/item/gemeentelijke-jo ngens-en-meisjeskostscholen 2711.html. [13] Website of ‘het Nut’ is www.nutalgemeen.nl/. [14] E.g. www.middel.org/canon-van-groningen/kapteyn/88-genealogie-kapteyn. [15] See genver.nl/index.htm. [16] Nr. 03.0934; beeldbank.ede.nl/atlantispubliek/default.aspx?modules=beeldban ken#media/434609/1. [17] FamilySearch, www.genver.nl.; Gelderland, Barneveld, file 5808804 (Gebo- orten 1849–1852), image 108/210. [18] Barneveldse Krant, 17 Febr. 1983. Gemeentearchief Barneveld. [19] Nr. ANS2.0095; beeldbank.ede.nl/atlantispubliek/default.aspx?modules= bee ldbanken#media/436904/1. [20] From Sterrenkijken bekeken, by A. Blaauw, J.A. de Boer, E. Dekker & J. Schuller tot Peursum-Meijer, Universiteits Museum Groningen (1983).

Chapter 2. Studies in Utrecht [1] Verloren (1997), ISBN 90-655-0557-1. [2] Tijdschrift voor de Geschiedenis van de Geneeskunde, Natuurwetenschappen, Wiskunde en Techniek, vol. 7, p. 32–48 (1984). [3] See web.science.uu.nl/NatuurkundigGezelschap/. [4] Boom, Meppel/Amsterdam (1985) www.dbnl.org/titels/titel.php?id=berk003 voet01. [5] Jensma & de Vries, op. cit. [6] Jensma & de Vries, op. cit. [7] See dap.library.uu.nl/. [8] See www.genealogy.ams.org/. [9] See www.knmi.nl/klimatologie/metadata/043 utrecht.html. [10] Bekking, Amersfoort, ISBN: 978-90-6109-323-7 (1993). [11] See www.sonnenborgh.nl/page=site.treenode/tree=english, from which part of this text has been taken. References 665

[12] See www.universiteitsmuseum.nl/Collectie/Detail/UG-5223?q=Oudemans en www.universiteitsmuseum.nl/Collectie/Detail/UG-5234?q=Hoek. [13] Astronomical Society of the Pacific Conference Series, No. 470 (2012). [aww. aspbooks.org/a/volumes/table of contents/?book id=520] [14] See www.universiteitsmuseum.nl/Collectie/Detail/UG-5212?q=Buys+Ballot and www.universiteitsmuseum.nl/Collectie/Detail/UG-5226?q=Grinwis. [15] Orbits of minor planets and comets can be studied using the NASA orbits tool of the Near-Earth Object Program at neo.jpl.nasa.gov/orbits/. [16] See www.conspiracyoflight.com/Hoek/Hoek Experiment.html. [17] Monthly Notices of the Royal Astronomical Society, 28, 131–150 (1868). [1868MNRAS..28..131H] [18] Copies of the Utrechtse Studenten Almanak are available in the library of Utrecht university. [19] Marcel Decker Inc. (2004), ISBN 0-8247-5629-0; e-book by Taylor & Francis e-Library, ISBN 0-203-02630-6. [20] See X5548mcise.uri.edu/sadd/mce565/notes.htm. [21] Annales de Chimie et de Physique, Troisieme` Serie,´ Tome LX, p. 449–478 (1860); eBook: books.google.nl/books?id=0eI3AAAAMAAJ. [22] University of Southampton, Southampton SO17 1BJ, United Kingdom. resou rce.isvr.soton.ac.uk/spcg/tutorial/tutorial/Tutorial files/Web-standing-membra ne.htm. See also www.southampton.ac.uk/soundwaves. [23] Soedel (op. cit.), Sadd (op. sit.), Jimin He & Zhi-Fang Fu, Modal Analysis, Butterworth-Heinemann, www.scribd.com/doc/50637604 /44/Vibra- tions-of-membranes. [24] See ru.wikipedia.org/wiki/%D0%A4%D0%B0%D0%B9%D0%BB:Zoellner Photometer.png (Wikimedia Commons) or www.vehi.net/brokgauz/all/006/ 6172.shtml.111. [25] Journal for the History of Astronomy, 31, 323–338, 2000, www.astronomyca. com/z/zollner-photometer.htm, [2000JHA....31..323S] and British Journal for the History of Science, 34, 439–451 (2001) respectively: apps.we bofknowl- edge.com/full record.do?product=WOS&search mode=full mode=GeneralSe arch&qid=1&SID=3Fnc1fKGHPbB7CA4hhh&WOS&searchpage=1&doc=1. [26] Bulletin of the Astronomical Institutes of the Netherlands, 1, 167–169 (1922). [1922BAN.....1..167V] [27] In six installments in ‘Popular Astronomy’ vol. 52 (1946), starting with [1946PA.....54..211W]. [28] MNRAS 19, 175–180 (1859) [1859MNRAS..19..175A], MNRAS 23, 166– 169 (1859), [1863MNRAS..23..166D], and MNRAS 30, 9–18 (1869). [1869MNRAS..30....9P]

Chapter 3. Astronomer in Leiden [1] Observatory, , 71, 128 (1951). [1951Obs....71..128] [2] From FamilySearch, www.genver.nl., Utrecht, Utrecht, File (6580428 Huw.- bijlagen 1879–1880 v/a mei t/m apr), Images 247–253/2518. 666 D Notes and References

[3] De lotingsinstrumenten voor de Nederlandse dienstplicht by F.Staarman and De dienstplicht op de markt gebracht; het fenomeen dienstvervanging in de negentiende eeuw by by E.W.R. van Roon. See alfredstaarman.nl/wp- content/uploads/Alfred-Staarman-De-lotingsinstrumenten-voor-de-dienstplic ht-in-de-collectie-van-het-Legermuseum-in-jaarboek-Legermuseum-Armame ntaria-nr.-31-1996-41-47.pdf and www.knhg.nl/bmgn2/R/Roon E. W. R. van - De dienstplicht op de markt gebracht. H.pdf [4] See also www.regionaalarchiefzutphen.nl/informatiebladen/47-militieregist ers. [5] Gemeentearchief Barneveld. [6] Astrophysical Journal 56, 145–153 (1922). [1922ApJ....56..145V] [7] Wetenschappelijke Bladen I., 257–295 (1923), see also J.C. Kapteyn und sein astronomisches Werk in Die Naturwissenschaften, Heft 45, 1–14 (1922). [8] Published by Leiden Observatory (1965), Waanders/De Kler, Zwolle (1983) and Leiden University (2011). [9] Studium, 4, 195–126 (2011); www.gewina-studium.nl/index.php/studium/ article/view/1545/7241. [10] Respectively www.dbnl.org/tekst/will078twee01 01/andsss.sagepub.com/ content/21/3/503.abstract. [11] See also www.strw.leidenuniv.nl/album1908/book info.html. [12] Astronomische Nachrichten 60, 273–286 (1863). [1863AN.....60..273K] [13] Respectively pages i-xlii [1868AnLei...1D...1.], xliii-lii [1868An Lei...1D ..43.], liii-lxv, [1868AnLei...1D..53.] and lxvi-lxxxvi.[1868An Lei...1D..66.] [14] nl.m.wikipedia.org/wiki/Bestand:Prof. H.G. van de Sande Bakhuyzen.jpg. [15] Verslag van de Staat der Sterrenwacht te Leiden en de aldaar volbrachte werkzaamheden, 1875–1876. [1876VeLdn..12....1V] [16] www.strw.leidenuniv.nl/outreach/strwarchief/observatoryarchives.php. [17] Verslag van den Staat der Sterrewacht te Leiden en van de aldaar volbrachte werkzaamheden (1875–1876). [1876VeLdn..12....1V] [18] See www.nationaalarchief.nl/. [19] Annalen van de Sterrewacht te Leiden, 1, liii-lxv (1868). [1868AnLei ...1D..53] [20] See www3.uni-bonn.de/. [21] Celestial Mechanics 36, 207–239 (1985). [1985CeMec..36..207F] [22] Journal of the Royal Astronomical Society of Canada, 85, 43–50 (1991). [1991JRASC..85...43B] [23] These Annual Reports (in Dutch) are available on ADS as [1875VeLdn ..11....1V, 1876VeLdn..12....1V, 1877VeLdn..13....1V and 1879VeLdn..15 ....1V] [24] www.museumboerhaave.nl/object/universeelinstrument-v10680/. [25] Verzeichniss der Instrumente der Sternwarte in Leiden, beim Anfange des Jahres 1868. [1868AnLei...1D..53.] [26] Published in two installments in Astronomische Nachrichten, 107, 49–60 and 97–112 (1883). [1883AN....107...49V] and [1883AN....107...97V] References 667

[27] From The Dutch Transit of Venus Expeditions of 1874 and 1882 by Robert van Gent, Anne Zandstra, Hans Hooijmaijers & Klaus Staubermann. [www.phys. uu.nl/$\sim$vgent/venus/cmm/dutch expeditions] Collectie Universiteitsmu- seum Utrecht, inv.nr. 0285–3994. [28] Astronomische Nachrichten, 95, 81–96 (1879). [1879AN.....95...81V] [29] Published by the U.S. Naval Observatory (1881). [1881USNOM..17C...1.] [30] Astronomische Nachrichten, 96, 119–128 (1879). [1879AN.....96..119D] [31] Summarized in Monthly Notices of the Royal Astronomical Society, 41, 317–324 (1881). [1881MNRAS..41..317G]

Chapter 4. Professor in Groningen [1] From Sterrenkijken bekeken, op. cit. [2] See Klaas van Berkel: In het voetspoor van Stevin; Bastiaan Willink: De tweede Gouden Eeuw and Origins of the Second Golden Age ...; Jensma & H. de Vries, Veranderingen in het hoger onderwijs...; P.A.J. Calje:´ Student, universiteit en samenleving;allop. cit. [3] See www.rug.nl/museum/galerij/portretten/hoogleraar/mulerius. [4] See hoogleraren.ub.rug.nl/?page=showPerson&type=hoogleraar&hoogleraar id=26&lang=nl. [5] See hoogleraren.ub.rug.nl/?page=showPerson&type=hoogleraar&hoogleraar id=91&lang=nl. [6] See irs.ub.rug.nl/ppn/108936023 and Digitale collecties van de Bibliotheek Rijksuniversiteit Groningen at facsimile.ub.rug.nl. [7] Jaarboek Rijks-Universiteit Groningen, 1877–1878, Wolters (1879), p. 39. [archive.org/details/jaarboekderrijk00grongoog] [8] Original in Universiteits Bibliotheek Groningen. [9] FamilySearch, www.genver.nl., Utrecht, Utrecht, File (6580300 Huwelijken 1879–1880), Image 166/576. [10] FamilySearch, www.genver.nl. [11] Lijst van (voornamelijk hervormde en lutherse) predikanten, hulppredikers, kandidaten, proponenten en theologanten. This belongs to J. Vree, Over- schot op de Nederlandse kandidatenmarkt: een bron van overzeese predikanten, hulppredikers, enz. (1829–1872), Documentatieblad voor de Nederlandse Kerkgeschiedenis na 1800 (DNK), 66, 17–53 (2007); www.hdc.vu.nl/nl/ onderzoek-en-publicaties/publicaties/documentatieblad/index.asp.

Chapter 5. From Kepler to Parallax [1] The full book is available at books.google.com.hk/books?id=KUE1AAAAcA AJ&printsec=frontcover&hl=zh-CN&source=gbs ge summar] r&cad=0#v=o nepage&q&f=false. [2] Second Edition, The Macmillan Company, London (1914). [3] Engelmann, Leipzig, 2 volumes (1870/1880). [4] The volumes can be accessed electronically on the Internet Archive through archive.org/details/handwrterbuchd$nn$vale with nn = 01,02,31,32,04. [5] Willmann-Bell (1993), ISBN 978-0943396408. 668 D Notes and References

[6] See www.dunsink.dias.ie/index.php?option=com content&view=category& id=97%3Astro-dunsink-observatory&layout=blog&Itemid=139&lang=en. [7] See also www.ﬁngaldublin.ie/interior-pages/activities-attractions-amp-confer ence/visitor-attractions/dunsink-observatory/. [8] Cambridge University Press (2010), ISBN 978-0-521-19267-5, page 236. [9] Available as preprint as arXiv-math/0510050v1; arxiv.org/pdf/math/0510050 .pdf [10] Respectively in Annales Scientiﬁques de l’E.N.S.,´ troisieme` serie,´ tome 10, 91–122 (1893) [archive.numdam.org/ARCHIVE/ASENS/ASENS 1893 3 10 /ASENS 1893 3 10 91 0/ASENS 1893 3 10 91 0.pdf] and Nieuw Archief voor de Wiskunde, xx, 116–127 (1893). [11] Newspaper archived at Research Library and Archives at the Pasadena Mu- seum of History. [12] Reproduced with permission from the Department of Manuscripts & Univer- sity Archives, University Library, Cambridge, UK. [13] Published in Memoirs of the Royal Astronomical Society, 48, 1–198 (1885). [1885MmRAS..48....1G] [14] These reports were published in the Monthly Notices of the Royal Ast- ronomical Society. The reports of 1885 to 1990 are in vol. 46, p.221 (1886); 47, 164 (1887); 48, 180 (1888); 49, 183 (1889); 50, 192 (1990) and 51, 212 (1991). [1886MNRAS..46..221.] [1887MNRAS..47..164.] [1888MN- RAS..48..180.] [1889MNRAS..49..183.] [1890MNRAS..50..192.] [1891MN- RAS..51..212.] [15] Monthly Notices of the Royal Astronomical Society, 55, 34–36 (1894). [1894MNRAS..55...34G] [16] Inaugural-Dissertation Kaiser-Wilhelms-Universitat¨ Strassburg (1901). [17] Internet Archive at archive.org/details/cu31924004071688. [18] Journal for the History of Astronomy, xxii, 267–296 (1991). [1991 JHA....22..267K] [19] Published in the Observatory, 40, 271–273 (1917). [1917Obs....40..271S] [20] Published in Bulletin of the Astronomical Institutes of the Netherlands, 3, 1–6 (1925). [1925BAN.....3....1D] [21] Abhandlungen der Koniglichen¨ Akademie der Wissenschafter zu Berlin, 1867, p.19 (1867) [22] Beschreibung der Registrir-Apparate der Sternwarte in Leiden, Annalen van de Sterrewacht te Leiden, 2, 6–18 (1870). [1870AnLei...2....6.] [23] The full reference is Sitzungsberichte der Mathematisch-Naturwissen- schaftlichen Classe der Kaiserlichen Akademie der Wissenschaften, Abtheilung II (Mathematik, Physik, Chemie, Mechanik, Meteorologie und Astronomie, LII, 546–546 (1866). [home.us.archive.org/ detailssitzungs- bericht193klasgoog] [24] See www.museumboerhaave.nl/object/meridiaankijker-v03471h/. [25] Astronomy & Astrophysics, 65, 77–81 (1978). [1978A&A....65...77L] References 669

[26] Maintained at the Centre de Donnees´ Astronomiques de, Strasbourg (simbad.u-strasbg.fr/simbad/). Ackowledgement: This research has made use of the SIMBAD database, operated at CDS, Strasbourg, France. [27] Memoirs of the Royal Astronomical Society, 48, 191 (1885) [28] Science, 3, 617–620 (1896). [1896Sci.....3..617F] [29] Publications of the Washburn Observatory, XI (1902). [archive.org/details/ meridiobservations11ﬂinrich] [30] Astronomische Nachrichten, 101, 69–72 (1881). [1881AN....101...69G] [31] See www.canonsociaalwerk.eu/1950 BenjaminSpockNL/img/cover%20Gerar d %20allebe.jpg. [32] See ﬂeximap.groningen.nl/gnmaps/monumenten/.

Chapter 6. Cape Photographic Durchmusterung [1] New York, Macmillan (1961) [2] Fourth edition, Macmillan (1977), ISBN 00-236-0190-6. [3] See American Institute of Physics Website: www.aip.org/history/cosmology/ tools/pic-spectroscopy-orion.htm. [4] In Mapping the Sky: Past Heritage and Future Directions, IAU Symposium 133, Paris, 143–148 (1988). [1988IAUS..133..143M] [5] The European Physical Journal: Historical Perspectives on Contemporary Physics. [2012arXiv1209.3563P] [6] Published in two parts in The Observatory, 10, 267–272 and 283–294 (1888). [1887Obs....10..267G] and [1887Obs....10..283G] [7] See gallica.bnf.fr/ark:/12148/cb343481087/date1882. [8] See www.saao.ac.za/public-info/pictures/comet/ [9] See www.nationalarchives.gov.uk/currency/results.asp#mid. [10] The Milky Way Galaxy, IAU Symposium 106, 25–42 (1985). [1985IAU S..106...25P] [11] Thomas Maclear & David Gill, London: Eyre & Spottiswoode for H.M.S.O., 1884. [1884cseo.book.....M] [12] See assa.saao.ac.za/html/his-obs-cape-gall dev.html. [13] See www.rug.nl/museum/geschiedenis/hoogleraren/kapteyn?lang=en. [14] Notes on visits to some continental observatories, The Observatory, 12, 344– 349 (1889). [1889Obs....12..344S] [15] It appeared in French in the Bulletin Astronomique Series I, 4, 361–380 (1887). [1887BuAsI...4..361G] [16] Naissance et Developpement de la Carte du Ciel en France in IAU Symposium 133: Mapping the Sky: Past Heritage and Future Directions, 29–32 (1988). [1988IAUS..133...29W] [17] London: Murray; available at archive.org/details/greatstarmapbein00turnuoft. [18] Bulletin Astronomique Serie I, 3, 161–164 (1886). [1886BuAsI...3..161G] [19] Bulletin Astronomique Serie I, 3, 321–324 (1886). [1886BuAsI...3..321G] [20] Paris : Gauthier-Villars (1887). See visualiseur.bnf.fr/Visualiseur?Destination =Gallica&O=NUMM-94857. 670 D Notes and References

[21] The full title is La Carte du Ciel – Histoire et actualite´ d’un projet scientiﬁque international, EDP Sciences SBN (2008), ISBN 978-2-7598-0057-5. [22] ‘Petite Histoire’ du Congres Astrophotographique de 1887 by A.M. Motais de Narbonne, in IAU Symposium 133: Mapping the Sky: Past Heritage and Future Directions, 129–133 (1988). [1988IAUS..133...129M] [23] See the paper by Motais de Narbonne, op. cit. [24] See answers.yahoo.com/question/index?qid=20070225055803AAc6VDO. [25] Journal of Astronomical History and Heritage, 12m 119–124 (2009). [2009JAHH...12..119L] [26] Reunion´ du Comite´ International Permanent pour l’Execution´ de la Carte Photographique du Ciel a` l’Observatoire de Paris by G. Bigourdan, Bul- letin Astronomique, Serie I, 6, 531–538 (1889) and 8, 461–468 (1891). [1889BuAsI...6..531B and 1891BuAsI...8..461B] [27] Mesure des Cliches´ d’apres` la Methode´ des Coordonnees´ Rectangulaires,Bul- letin de Comite´ International Permanent de la Carte du Ciel, 164–204 (1889) [28] A revisit to the region of Collinder 132 using Carte du Ciel and Astr- ographic Catalogue plates by R.B. Orellana, M.S. de Biasi, I.H. Bus- tos Fierro & J.H. Calderon,´ Astronomy & Astrophysics, 521, A39 (2010). [2010A&A...521A..39O] [29] Carte du Ciel: Call for the Compilation of a Complete Inventory of Publica- tions, ASP Conference Series, 377, 369 (2007) [2007ASPC..377..369R] and her website at www.astropa.unipa.it/Library/CarteduCiel/index.htm. [30] David Gill and celestial photography, op. cit. [31] Annals of the Cape Observatory, South Africa, 9, 0.1–1.63 (1903). [1903An Cap...9....1I] [32] Annals of the Cape Observatory, South Africa, 9, 3.1–3.86 (1903). [1903An Cap...9....3G] [33] Volume 7, pp.235–240. [34] Cf. Groningen, Town and Provincial Archives, inventory no 83: prison archives, documents concerning the employment of prisoners. [35] A.S. Eddington, Jacobus Cornelius Kapteyn, The Observatory, 45, 261–265 (1922), [1922Obs ....45..261.], quotation p. 262. [36] For Domela’s term in prison, see for instance Jan Meyers (1993), Domela, een Leven op Aarde. Leven en Streven van Ferdinand Domela Nieuwenhuis (Amsterdam), 163–176. [37] A.S. Eddington, “Jacobus Cornelis Kapteyn, 1851–1922”, Proceedings Royal Society London, Section A, 102, xxix-xxxv (1922), quotation p.xxxi.

Chapter 7. An Astronomical Laboratory [1] See en.wikisource.org/wiki/Herschel, William (DNB00). [2] www.atlasoftheuniverse.com/hr.html and en.wikipedia.org/wiki/File:HRDia gram.png. This ﬁle is licensed under the Creative Commons Attribution-Share Alike 2.5 Generic license. References 671

[3] See www.eso.org/public/images/eso1118a/ and www.noao.edu/outreach/aop/ observers/n891.html (Minimum credit line: Dale Cupp/Flynn Haase/NOAO/ AURA/NSF). [4] Respectively New York, Norton [1964, c1963] (DLC) 64010566; Princeton Univ. Press, ISBN 978-0-691-1483-5; Cambridge Univ. Press, ISBN 798-1- 01838-9. [5] See commons.wikimedia.org/wiki/File:Bolton-herschel.jpg, commons.wiki media.org/wiki/File:Herschel Caroline 1829.jpg and commons.wikimedia. org/wiki/File:John Herschel South African expedition.png. These images are in the public domain (copyright has expired). [6] See commons.wikimedia.org/wiki/File:PSM V09 D079 Herschel 40 foot tel escope at slough.jpg (see previous note). [7] Philosophical Transactions of the Royal Society of London, 75, 213–266 (1785). [1785RSPT...75..213H] [8] Astronomy & Astrophysics, 157, 230–244 (1986), [1986A&A...157..230V] [9] Philosophical Transactions of the Royal Society of London, 107, 302–331 (1817). [1817RSPT..107..302H] [10] Imperial Academy of Sciences of Saint Petersburg, re-issued recently under ISBN-10 11-4404-207-0. [11] The book is available on archive.org/details/popularastronomy031620mbp. [12] The original image is out of copyright. I gratefully acknowledge the preser- vation and scanning by ‘University of Cambridge, Institute of Astronomy Li- brary’. See www.repository.cam.ac.uk/handle/1810/225982. [13] Verslag van den Staat der Sterrewacht te Leiden en van de aldaar volbrachte werkzaamheden (1886–1888). [1888VeLdn..24....1V] [14] Verslag van den Staat der Sterrewacht te Leiden en van de aldaar volbrachte werkzaamheden (1890–1892). [1892VeLdn..28....1V] [15] See www.grunn.nl/fotoalbum/img/oude boteringestraat gerechtsgebouw.gif [16] Monthly Notices of the Royal Astronomical Society, 46, 237–238 (1886). [1886/MNRAS..46..237V] [17] Bulletin Astronomique, Ser. I, 12, 97–106 (1895). [1895BuAsI..12...97V] [18] Astronomische Nachrichten, 146, 209–21 (1898). [1898AN....146..209V] [19] www.beeldbankgroningen.nl Identiﬁcatienummer: NL-GnGRA 1785 610. [20] Astronomische Nachrichten, 124, 177 (1890). [1890AN....124..177H] [21] Published in the Observatory, Vol. 25, pp. 158–161 (1902). [1902Obs ....25..158C] [22] The Observatory 21, 106 (1898). [1898Obs....21..103.] [23] The Observatory, 21, pp. 409–410 (1898). [1898Obs....21..409.] [24] DSS2 is available at the Space Telescope Science Institute Website at stdatu.stsci.edu/dss/. For a Web animation, see groups.google.com/a/ googleproductforums.com/forum/?fromgroups#!msg/gec-sky/kulxqfbRZvQ/ JaolC-O5EDkJ. [25] The Observatory, 22, 99–101 (1899). [1898Obs....22...99G] 672 D Notes and References

[26] E. Kotoneva, E., K. Innanen, K., P.C. Dawson, P.R. Wood & M. de Robertis: A study of Kapteyn’s star, Astronomy & Astrophysics, 438, 957–962 (2005). [2005A&A...438..957K] [27] Astronomical Journal 112, 1595–1613 (1996). [1996AJ....112.1595E] [28] Press release heic0809, 2 April 2008; see www.spacetelescope.org/news/ heic0809/. [29] Boston, Harvard Univ. Press (1932). The 1934 Dutch version, published by van Stockum & Zoon, Den Haag, is available electronically from the ‘Digital Library of Dutch Literature’ at www.dbnl.org/tekst/sitt003kosm01 01/. [30] E. Wylie-de Boer, K.C. Freeman and M. Williams, Astronomical Journal, 139, 636–645 (2010). [2010AJ....139..636W] [31] Guillem Anglada-Escude,´ et al., Two planets around Kapteyn’s star: a cold and a temperate super-Earth orbiting the nearest halo red-dwarf, eprint arXiv. [2014arXiv1406.0818A] [32] Letters of J.C. Kapteyn.[www.helsinki.ﬁ/astro/history/donner/jck.html] [33] Monthly Notices of the Royal Astronomical Society, 95, 343–347 (1935). [1935MNRAS–95..343.] [34] Homepage of the Share Initiative is www.tsieuropean.co.uk. [35] Monthly Notices of the Royal Astronomical Society, 59, 341–345 (1899). [1899MNRAS..59..341D] [36] Annals of the Cape Observatory, 8, 2.i-2.175 (1900). [1900AnCap...8....2G] [37] The thesis is not available in electronic form. However, it was published in a different form as Determination of the mass of Jupiter and elements of the orbits of its satellites’ by W. de Sitter, D. Gill & W.H. Finlay, Annals of the Cape Observatory, 12, 1.1–1.173 (1915). [1915AnCap..12....1D] [38] Monthly Notices of the Royal Astronomical Society, 91, 706–738 (1931). [1931MNRAS..91..706D] [39] From www.noao.edu/image gallery/html/im0552.html. Credit line: National Optical Astronomy Observatory/Association of Universities for Research in Astronomy/National Science Foundation [40] W. de Sitter, Publications of the Astronomical Laboratory Groningen, 15, 3–12 (1906). [1906PGro....15...1D]

Chapter 8. Colors and Motions [1] See kaarten.abc.ub.rug.nl/ and atlas1868.nl/dr/vries.html,alsoatfacsimile.ub. rug.nl. [2] Published in Science, 5, 777–785 (1897). [1897Sci.....5..777N] [3] The Autocrat of the Breakfast–Table is available at archive.org/details/auto cratbreakfa11holmgoog. [4] See archive.org/details/writingsoliverw14holmgoog and archive.org/details/ writingsoliverw11holmgoog. [5] The website of the Koninklijk Natuurkundig Genootschap is www.kng-gro ningen.nl. [6] See nl.wikipedia.org/wiki/Hendrik Jacob Herman Modderman sr. References 673

[7] Groningen: Gebroeders Hotsema. [www.dwc.knaw.nl/pub/tjadenmodderman 1901.pdf] [8] Profiel, Bedum, ISBN 90-529-4220-X, see also www.kng-groningen.nl/ boekjub.htm. [9] Verloren (2012), ISBN 97-8908-704-194-6. [10] See www.rug.nl/museum/galerij/portretten/hoogleraar/huizinga. [11] The website of the Nederlandsch Natuur- en Geneeskundig Congres is www. nngc.nl. [12] Astronomische Nachrichten, 147, 1–12 (1898). [1898AN....147....1S] [13] Publications of the Astronomical Laboratory Groningen, 3, 23–26 (1900). [1900PGro...23D] [14] en.wikipedia.org/wiki/File:Obafgkm noao big.jpg. ‘This file is in the public domain because it was solely created by NASA’. [15] Annals of Harvard College Observatory, 27, 1–388 (1890). [1890AnHar ..27....1P] [16] Philosophical Transactions of the Royal Society of London, 73, 247–283 (1783). [1783RSPT...73..247H] [17] Local kinematics and the local standard of rest by R. Schonrich,¨ J. Binney & W. Dehnen, Monthly Notices of the Royal Astronomical Society, 403, 1829– 1833 (2010). [2010MNRAS.403.1829S]. [18] See www.iau.org/public/themes/constellations/. See also www.iau.org/ copyright/. [19] Knowledge, April 1, 66–68, and May 1, 84–85 (1898). [20] Credit: ESA/Hubble & Digitized Sky Survey 2. Davide De Martin (ESA/Hubble). [spacetelescope.org/images/heic1112f/] [21] Publikationen des Astrophysikalischen Observatoriums zu Potsdam, vol. 7 (1892). [articles.adsabs.harvard.edu/cgi-bin/iarticle query?journal=POPot& volume=0007&type=SCREEN THMB] [22] Versuch einer Ableitung der Bewegung des Sonnensystems aus den Pots- damer spectrographischen Beobachtungen, Astronomische Nachrichten, 132, 81 (1893). [1893AN....132...81V] [23] Astronomical Journal, 17, 41–44 (1896). [1896AJ.....17...41N] [24] Astronomical Journal, 20, 1–6 (1899). [1899AJ.....20....1N] [25] New York, G.P. Putnam’s sons (1901), op. cit. [26] There are two installments in the Observatory, Vol. XXX, 299–306 and 335– 339 (1907). [1907Obs....30..299G] and [1907Obs....30..335G] [27] Celestial Mechanics, 36, 207–239 (1985). [1985CeMec..36..207F] [28] Sdu Uitgevers, Den Haag (2000), ISBN 90 12 08622 1; www.dbnl.org/tekst/ bank003190001 01/bank003190001 01 0010.php. [29] Heidelberg: Carl Winter (1910). [30] Persoonlijke Herinneringen aan de Stad Groningen rond de Eeuwwisseling, Groningsche Volksalmanak voor 1957, pp. 33–52. [31] See www.genealogieonline.nl/genealogie-baert-cornelis-kalshoven/I284.php. [32] In: Universitas Groningana MCMXIV – MCMLXIV, Groningen. 176–183. [33] In: Verzamelde werken, VI, 336–338 (Haarlem, 1950), 336–338. 674 D Notes and References Chapter 9. Star Streams [1] Respectively The old-nova GK Per (1901). IV – The light curve since 1901, Astronomy & Astrophysics Supplement Series, 54, 393–403 (1983), [1983A&AS...54..393S], and The old-nova GK Per (1901). I – Determina- tion of the orbital period, Astronomy & Astrophysics, 99, 392–393 (1981). [1981A&A....99..392B] [2] Photographs and measures of the nebula surrounding Nova Persei,Astro- physical Journal, 16, 249–256 (1902). [1902ApJ....16..249.] Reproduced from plates relocated in the archives of Lick Observatory and scanned. [3] Astrophysical Journal, 16, 198–202 (1902). [1902ApJ....16..198H] [4] www.noao.edu/outreach/aop/observers/GKper.html. [5] Annales d’Astrophysique, 2, 271–302 (1939). [1939AnAp....2..271C] [6] The volumes up to 1950 can be examined through www.dwc.knaw.knaw.nl/ toegangen/digital-library-knaw/?pagetype=bundel. [7] www.astro.rug.nl/$\sim$vdkruit/jea3/homepage/voetbal.pdf, 2006. [8] KNAW Proceedings, 4, 221–232 (1902). [www.dwc.knaw.nl/DL/publications/ PU00014272.pdf] [9] Astronomische Nachrichten, 158, 167–174 (1902). [1902AN....158..167S] [10] Astronomical Journal, 21, 161–168 (1901). [1901AJ.....21..161B] [11] Precession and solar motion, First and Second Paper, Astronomical Journal, 26, 95–99 & 111–122 (1910). [1910AJ.....26...95B] and [1910AJ.....26..111B] [12] The 1888 version is available on archive.org/details/textbookofgenera00youn, the 1898 version as atextbookgenera05youngoog on the same site. [13] Astrophysical Journal, 151, 393–409 (1968). [1968ApJ...151..393S] [14] Inflation calculator at www.davemanuel.com/inflation-calculator.php. [15] The effects of the 1904 North Atlantic fare war upon migration between Europe and the United States by Drew Keeling, www.iga.ucdavis.edu/Research/All- UC/conferences/2006-fall/Keeling.pdf. [16] See archive.org/details/cu31924015340114. [17] Volume VIII, Astronomy and Earth Sciences, edited by Howard J. Rogers (1908). [archive.org/details/internationalcon08inteiala] [18] See exhibits.slpl.org/lpe/data/LPE240025391.asp?thread=240029400. [19] The URL is archive.org/details/internationalcon08inteiala. [20] The URL is archive.org/details/reportofbritisha06scie. [21] Popular Astronomy, 31, 429–440 (1923). [1923PA.....31..429M] [22] Monthly Notices of the Royal Astronomical Society, 82, 432–438 (1922). [1922MNRAS..82..432E] [23] The Observatory, 45, 261–265 (1922). [1922Obs....45..261.] [24] See en.wikisource.org/wiki/Popular Science Monthly/Volume 66/November 1904/The Progress of Science. [25] www.beeldbankgroningen.nl/beeldbank/; identificatienummer: NL-GnGRA 1986 2563), Foto collectie RHC Groninger Archieven (1986–2563). [26] www.groningeninbeeld.nl/Markten/images/MRK 010.jpg. References 675 Chapter 10. Selected Areas [1] Monthly Notices of the Royal Astronomical Society 62, 334–343 (1902). [1902MNRAS..62..334.] [2] Publications of the Astronomical Society of the Pacific, 14, 97–102 (1902). [1902PASP...14...97G] [3] A history and description of the Royal Observatory, Cape of Good Hope,by Sir David Gill, K.C.B.; London: His Majesty’s Stationary Office (1913). [4] Bulletin Astronomique, 23, 480 (1906). [1906BuAsl–23..480] [5] See www.eso.org/public/images/yb southerncross cc/. [6] The Observatory, 29, 129–134 (1906). [1906Obs....29..129.] [7] Monthly Notices of the Royal Astronomical Society, 67, 34–63 (1906). [1906MNRAS..67...34E] [8] Monthly Notices of the Royal Astronomical Society, 65, 428–457 (1905). [1905MNRAS..65..428D] [9] Nachtrichten der Konigliche¨ Gesellschaft der Wissenschaften zu Gottingen,¨ Mathematisch-physikalische Klasse (1907). [10] Proceedings of the Royal Society of Edinburgh, 28, 231–238 (1908), summary in The Observatory, 31, 200–204 (1908). [1908Obs....31..200D] [11] Astrophysical Journal, 14, 297–312 (1901). [1901ApJ....14..297N] [12] Cambridge University Press, ISBN 0 521 35363 7 (1993). [13] Transactions of the International Union for Cooperation in Solar Research, 1, 5–10 (1906). [1906TIUCS...1....5.] [14] bookhistory.harvard.edu/takenote/sites/default/files/attachments/ Edward\Pickering.jpg,reproducedwithpermission. [15] Hoitsema Brothers, Groningen (1923). [16] Bulletin of the Astronomical Institutes of the Netherlands, 6, 75–81 (1930). [1930BAN.....6...75V] [17] B.T. Lynds in: Astronomical Society of the Pacific Leaflets, Vol. 9, No 412, 89–96 (1963), [1963ASPL....9...89L], A. Blaauw & T. Elvius, T. in the com- pendium Stars and Stellar Systems, Volume V: Galactic Structure. ed. A. Blaauw and M. Schmidt, University of Chicago Press, 589–597 (1965). [18] See dasch.rc.fas.harvard.edu/telescopes.php, reproduced with permission. [19] From Sterrenkijken bekeken, op. cit. [20] From A. Schwassmann & P.J. van Rhijn (1935), [1935bsdn.book.....S.] [21] Bd.1: Eichfeld 1 bis 19, Deklination +90 deg., +75 deg., +60 deg. (1935); Bd.2: Eichfeld 20 bis 43, Deklination +45 deg. (1938); Bd.3: Eichfeld 44 bis 67, Deklination +30 deg. (1947); Bd.4: Eichfeld 68 bis 91, Deklination +15 deg. (1951); Bd.5: Eichfeld 92 bis 115, Deklination 0 deg. (1953). Published by the Hamburger Sternwarte in Bergedorf. [22] Bd.I. Pol und Zone -75 deg. (1929); Bd. II. Zone -60deg. (1930); Bd. III. Zone -45deg. (1931); Bd. IV. Zone -30deg. (1935); Bd. V. Zone -15deg. (1938); published by the Potsdam Astrophysikalische Observatorium. [23] Faint standards of photographic magnitude for the Selected Areas, Pub- lications of the Astronomical Society of the Pacific, 26, 51–52 (1914). [1914PASP...26...51S] 676 D Notes and References

[24] Studies based on the colors and magnitudes in stellar clusters, Astrophysical Journal, 45, 118–141 (1917). [1917ApJ....45..118S] [25] Stellar populations and the distance scale: the Baade-Thackeray correspondence, Journal for the History of Astronomy, 31, 29–36 (2000). [2000 JHA....31...29F] [26] Publications of the Kapteyn Astronomical Laboratory at Groningen, 38, 1–77 (1925). [1925PGro...38D...1V] [27] In Sterrenkijken bekeken, A. Blaauw, J.A. de Boer, E. Dekker & J. Schuller tot Peursum-Meijer, Universiteits Museum Groningen (1983). [28] Photograph at 194.171.109.12/cat toon foto.php?registratiecode=VFOTNL02 9009&exact=JA&cat=VFOT&zoekterm=Kapteyn, reproduced with permission.

Chapter 11. Extinction [1] Annals of the Astronomical Observatory of Harvard College, 48, 149–185 (1903). [1903AnHar..48..149P]. [2] Popular Astronomy, 1, 224–226 (1893). [1893PA...... 1..224V] [3] M.A.C. Perryman, A.G.A. Brown, Y. Lebreton, A. Gomez, C. Turon, G. Cayrel de Strobel, J.C. Mermilliod, N. Robichon, J. Kovalevsky & F. Crifo, Astronomy & Astrophysics, 331, 81–120 (1998). [1998A&A...331...81P] [4] See www.spacetelescope.org/images/heic0515c/. [5] See hoogleraren.ub.rug.nl/?page=showPerson&type=hoogleraar&hoogleraar id=1876&lang=en\?iframe=true. [6] Algemeen Nederlands Tijdschrift voor Wijsbegeerte en Psychologie, 53, 113–114 (1961). [7] Astronomical Journal, 26, 31–36 (1908). [1908AJ.....26...31B] [8] Astronomical Journal, 24, 43–49 (1904). [1904AJ.....24...43C] [9] Darkness at Night: A riddle of the Universe, Harvard University Press (1987), ISBN 978-0-674-19270-6. [10] Page 185, bottom in [1903AnHar..48..149P]. [11] T. Credner & S. Kohle, www.allthesky.com. With permission. [12] Press Release ESO1103, Jan. 2011; www.eso.org/public/news/eso1103/. [13] I quote from the 1893 edition, §§788 and 792. Available at archive.org/det ails/outlinesofastron00hersuoft. [14] See www.spacetelescope.org/projects/ﬁts liberator/ﬁtsimages/john corban 4/. [15] ESO Press Release 9934, Febr. 1999; www.eso.org/public/news/eso9934/. [16] Both op. cit., respectively www.archive.org/details/starsstudyofuniv00newciala and archive.org/details/handwrterbuchd31vale. [17] Popular Astronomy, 14, 475–488 (1906). [1906PA.....14..475P] [18] See hubblesite.org/gallery/album/galaxy/pr2005012a/ and /pr2006010a/. [19] Astrophysical Journal, 12, 136–158 (1900). [1900ApJ....12..136E] [20] English translations at www.dwc.knaw.nl/toegangen/digital-library-knaw/? pagetype=publDetail&pId=PU00013940 and pId=PU00013941. [21] Popular Astronomy, 14, 579–583 (1906). [1906PA.....14..579B] [22] Astrophysical Journal, 37, 105–118 (1913). [1913ApJ....37..105E] References 677

[23] Veroffentlichungen¨ der Koniglichen¨ Sternwarte zu Bonn, no. 1, (1895), 1–97. Listed in ADS [adsabs.harvard.edu/abs/1895VeBon...1....1M] but no electronic copy available to my knowledge. [24] Annals of Harvard College Observatory, 28, 1–128 (1897). [1897AnHar ..28....1M] [25] APlotofUBVDiagramby B. Nicolet, Astronomy & Astrophysics Supple- ment, 42, 283–283 (1980). [1980A&AS...42..283N] [26] Annals of the Astronomical Observatory of Harvard College, 50, 1–252 (1908). [1908AnHar..50....1] [27] Monthly Notices of the Royal Astronomical Society, 69, 61–72 (1908), [1908MNRAS..69...61T] and Annals of Harvard College Observatory, 59, 157–186. [1912AnHar..59..157K] [28] Astrophysical Journal, 36, 169–227 (1912). [1912ApJ....36..169P.] [29] The British Journal for the History of Science, 30, 337–355 (1997). [dash.harvard.edu/bitstream/handle/1/3716614/Voskuhl Recreating.pdf?seque nce=2] [30] Proceedings of the National Academy of Sciences of the United States of America, 2, 12–15 (1916). [1916PNAS....2...12S] [31] Proceedings of the Royal Society of London. Series A, Containing Pa- pers of a Mathematical and Physical Character, 111, 424–456 (1926). [1926RSPSA.111..424E, see also rspa.royalsocietypublishing.org/content/ 111/759/424.full.pdf] [32] Bulletin of the Astronomical Institutes of the Netherlands, 4, 123–128 (1928). [1928BAN.....4..123V] [33] See www.rigb.org/registrationControl?action=home. [34] Publications of the Astronomical Society of the Pacific, 42, 214–227 (1930). [1930PASP...42..214T] [35] www.beeldbankgroningen.nl/beeldbank/;identificatienummer:NL-GnGRA 1986 372. With permission from Aviodrome Lelystad Airport. [36] www.beeldbankgroningen.nl/beeldbank/; identificatienummer: NL-GnGRA 1785 6866. Foto P. Kramer, RHC Groninger Archieven (1785–6866). [37] www.groningerarchieven.nl, reproduced on groningertram.com/de-groningertram-vroeger/). [38] www.beeldbankgroningen.nl/beeldbank/; identificatienummer: NL-GnGRA 1986 2921), Foto collectie RHC Groninger Archieven (1986–2921).

Chapter 12. Students [1] Also on Jet Katgert-Merkelijn’s homepage: home.strw.leidenuniv./nl∼merke/ lyn/1926 Groningen.html. [2] De Bouw der Sterrenstelsels (1931), Wolters, Groningen. [3] Annual Reviews of Astronomy & Astrophysics, 19, 1–5 (1981). [1981 ARA&A..19....1O] [4] Universitas Groningana MCMXIV-MCMLXIV, Groningen (1964), 176–183. 678 D Notes and References

[5] The home page of the Mathematics Genealogy Project is at genealogy.math.ndsu.nodak.edu/index.php. Kapteyn is #112114, Haga #114664 and Schoute #49650. The completeness of the MGP is far from guaranteed. [6] Astronomische Nachrichten, 16, 43–50 (1838). [1838AN.....16...43A] [7] Kindly made available by Dr. Matsuoka, [email protected]. [8] Lund panorama reproduced with permission, www.astro.lu.se/Resources/ Vintergatan/; van der Kruit (1986) op. cit.. [9] Astronomy & Astrophysics, 157, 230–244 (1986). [1986A&A...157..230V] [10] Astrophysical Journal, 14, 297–312 (1901). [1901ApJ....14..297N] [11] Cosmic optical background: The view from Pioneer 10/11 by Y. Matsuoka, N. Ienaka, K. Kawara & S. Oyabu, Astrophysical Journal, 736, article id. 119, 14 pp. (2011). Picture kindly made available by Dr. Matsuoka. [12] Digital Special Collections. socrates. leidenuniv.nl/R?func=search-simple&lo cal base=gen01-disc. [13] University of Chicago Press; 1st edition (1997), ISBN-13: 978-0226468860. [14] Information handling in astronomy – Historical vistas, Ed. A. Heck, Astro- physics and Space Science Library, 285, 267–273, Dordrecht: Kluwer (2003). [2003ASSL..285..267J]

Chapter 13. Mount Wilson [1] See en.wikipedia.org/wiki/Mount Wilson Toll Road. [2] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/1868/rec/26. [3] Respectively: The MIT Press (1972), ISBN-10 0262230496 and American Institute of Physics (1994), ISBN-10 1563962497. [4] Respectively W.S. Adams, Astrophysical Journal, 87, 369–388 (1938) and H.D. Babcock, Publications of the Astronomical Society of the Paciﬁc, 50, 156–165 (1938). [1938ApJ....87..369A and 1938PASP...50..156B] [5] Proceedings of the American Academy of Arts and Sciences, 57, 478–482 (1922). [6] See www.dudleyobservatory.org/archives/archives astrojrnl.htm. [7] Astronomical Journal, 25, 169–175 (1907). [1907AJ.....25..169C] [8] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/500/rec/87. [9] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/1143/rec/ 12. [10] From www.astro.caltech.edu/palomar/images/w100.jpg, reproduced with permission. [11] Carnegie Institution of Washington Year Book, vol. 6 (1907), page 136–137. [12] See The Observatory, 30, 243–245 (1907). [1907Obs....30..243] [13] See www.measuringworth.com/datasets/exchangeglobal/result.php. [14] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/399/rec/69. [15] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/431/rec/91. [16] www.ﬂora-and-sam.com/pages/ImmigrationShips.htm#rotterdam. [17] See en.wikipedia.org/wiki/Transcontinental Express [18] Taken from wikimapia.org/9752676/Kapteyn-Cottage. References 679

[19] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/1124/rec/ 20. [20] The Fourth Conference of the International Union for Co-operation in Solar Research, H.C. Wilson, Publications of the Astronomical Society of the Pa- cific, 22, 169–179 (1910); The Mount Wilson Conference of the Solar Union, C.A. Chant, C. A. Journal of the Royal Astronomical Society of Canada, 4, 356–372 (1910). [1910PASP...22..169W and 1910JRASC...4..356C] [21] See [1911TIUCS...3....1.] for opening pages; use ADS to find further parts. [22] According to the Photographic Archive of the University of Chicago Library, see photoarchive.lib.uchicago.edu/db.xqy?one=apf6--04419-017.xml. [23] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/1140/rec/6, identification of McBrids photoarchive.lib.uchicago.edu/db.xqy?one=apf6-04 419-017.xml. [24] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/855/rec/3. [25] Picture and permission provided by Susanne Elisabeth Nørskov, AU Library, Fysik & Steno, Institut for Fysik og Astronomi, Aarhus Universitet, Denmark. [26] See www.phys-astro.sonoma.edu/brucemedalists. [27] Astronomische Nachrichten, 292, 142 (1970). [1970AN....292..142S]

Chapter 14. Tides, Statistics and the Art of Discovery [1] From The Chemical News and Journal of Physical Science (22 Sep 1916). [2] See www.rijkswaterstaat.nl/geotool/astronomisch getij.aspx. [3] International Statistical Review 77, 96–117 (2009). [4] See hoogleraren.ub.rug.nl/?page=showPerson&type=hoogleraar&hoogleraar id=108&lang=enand&hoogleraar id=125&lang=en. [5] E. Limpert, W.A. Stahel & M. Abbt, BioScience 51, 341–352 (2001). [6] J. Aitchison & J.A.C. Brown, Cambridge University Press (1966). [7] Annals of the Astronomical Observatory of Harvard College, 48, 149–185 (1903). [1903AnHar..48..149P] [8] Philosophical Transactions of the Royal Society, London, A186, 343–414 (1895). [9] Biometrika, 4, 169–212 (1905). [10] Journal of the Royal Statistical Society, 61, 670–700 (1898). [11] Biometrika, 5, 168–171 (1906). [12] Statistica Neerlandica, 255–25813 (2008); onlinelibrary.wiley.com/doiu/10. 1111/j.1467--9574.1959.tb00870.x/pdf. [13] See www.vanuven.nl, homepage of the Van Uven Stichting. [14] Gerwina, 15, 195–207 (1992). [15] Extrait du T. IX des Memoires´ present´ es´ par divers Savants a` l’Academie´ Royale des Sciences de l’Institut de France, 9, 255–332. (1846). A version from 1884 can be downloaded using download.digitale- sammlungen.de/BOOKS/pdf download.pl?id=bsb10053322. [16] Biometrika, 13, 25–45 (1920). [17] In 3 volumes, published in 4 parts, Cambridge University Press. 680 D Notes and References

[18] www.beeldbankgroningen.nl/beeldbank/; identiﬁcatienummer: NL-GnGRA 1986 446. Foto collectie RHC Groninger Archieven (1986–446). [19] www.beeldbankgroningen.nl/beeldbank/; identiﬁcatienummer: NL-GnGRA 1785 5645. Foto collectie RHC Groninger Archieven (1785–5645).

Chapter 15. First Attempt [1] Astrophysical Journal, 33, 64 (1911). [1911ApJ....33...64A] [2] Astrophysical Journal, 35, 163 (1912). [1912ApJ....35..163A] [3] See cdm16003.contentdm.oclc.org/cdm/singleitem/collection/p15150coll2/id/ 1136/rec/3 [4] Astrophysical Journal, 42, 172–194 (1915). [1915ApJ....42..172A] [5] Lick Observatory Bulletin 229 (1913). [1913LicOB...7..113C] [6] NASA, ESA, and the Hubble Heritage Team (STScI/AURA), heritage.stsci. edu/2013/13/index.html. [7] See www.exploratorium.edu/eclipse/1901.html for a brief report. [8] Recherches Astronomiques de l’Observatoire d’Utrecht, 7, iii-P4.1 (1917). [1917RAOU....7....1N] [9] See Harvard College Observatory Circular, 185, 1 (1914). [1914HarCi .185....1P] [10] E.C. Pickering: Revised Harvard photometry : a catalogue of the positions, photometric magnitudes and spectra of 9110 stars, mainly of the magnitude 6.50, and brighter observed with the 2 and 4 inch meridian photometers,An- nals of the Astronomical Observatory of Harvard College, 50, i-194 (1908). [1908AnHar..50....1P] [11] Verslag van den staat der Sterrenwacht te Leiden en van de aldaar volbrachte werkzaamheden (1910–1912), vol. 49. [1913VeLdn..49....1V] [12] Some peculiarities in the motions of the stars, Lick Observatory bulletin 196 (1911). [1911LicOB...6..125C] [13] Washington, D.C.: Carnegie Institution (1910). [1910pgcs.book.....B], available at archive.org/details/preliminarygener00carnrich. [14] Proceedings of the National Academy of Sciences, 1, 417 (1915). [1915 PNAS....1..417A] [15] ASP Conference Proceedings, 471, 205–215 (2013). [2013ASPC..471..205G] [16] Astronomische Nachrichten, 179, 373–380 (1909). [1909AN....179..373H] [17] Relations between the spectra and other characteristics of the stars, Popu- lar Astronomy, 22, 275–294 and 331–351 (1914). [1914PA.....22..275R and 22..331R] [18] The radial velocities of one hundred stars with measured parallaxes, Astro- physical Journal, 39, 341–349 (1914). [1914ApJ....39..341A] [19] Some spectral criteria for the determination of absolute stellar magnitudes Astrophysical Journal, 40, 385–398 (1914). [1914ApJ....40..385A] [20] I. A quantitative method of classifying stellar spectra, Proceedings of the Na- tional Academy of Sciences, 2, 143–147; II. A spectroscopic method of determining stellar parallaxes, ibid., 147–152; III. application of a spectroscopic method of determining stellar distances to stars of measured parallax, ibid., References 681

152–157; IV. Spectroscopic evidence for the existence of two classes of M type stars, ibid., 157–163 (1916). [1916PNAS....2..143A], [2..147A], [2..152A] and [2..157A] [21] Publications of the Astronomical Society of the Paciﬁc, 28, 61–69 (1916). [1916PASP...28...61A] [22] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/1874/rec/3. [23] Astrophysical Journal, 45, 293–305 (1917). [1917ApJ....45..293A] [24] Astrophysical Journal, 47, 7–37 (1918). [1918ApJ....47....7S] [25] Astrophysical Journal, 59, 228–251 (1924) and ibid., 61, 363–388 (1925). [1924ApJ....59..228S and 1925ApJ....61..363S] [26] Astrophysical Journal, 46, 313–339 (1917). [1917ApJ....46..313A] [27] Contributions from the Mount Wilson Observatory / Carnegie Institution of Washington, No 170, 1–12 (1919). [1919CMWCI.170....1S] [28] Publications of the Kapteyn Astronomical Laboratory Groningen, 34, 1–80 (1923) and 37, 1–31 (1925). [1923PGro...34....1V] and [1925PGro...37....1V] [29] Citations resp. from pp. 226, 227 of the Legacy and pp. 223, 326 and 331 in DeVorkin’s Russell biography. [30] Bulletin of the Astronomical Institutes of the Netherlands, 3, 35–41 (1925). [1925BAN.....3...35T] [31] See rasathane.en.ankara.edu.tr/. [32] Ankara, ISBN 978-605-87419-0-4; www.bitav.org.tr/TR/Genel/dg.ashx? DIL=1&BELGEANAH=176&DOSYAISIM=EAK Life Story Book CGO3. pdf and Egbert Adriaan Kreiken: pionier in de Turkse sterrenkunde, Zenit, januari 2013, 14–18. [33] The universe at faint magnitudes. I - Models for the galaxy and the predicted star counts, Astrophysical Journal Supplement Series, 44, 73–110 (1980). [1980ApJS...44...73B] [34] Astronomy and Astrophysics, 157, 230–244 (1986), section 5.5. [1986 A&A...157..230V] [35] Publications of the Kapteyn Astronomical Laboratory Groningen, 43, 1–104 (1929). [1929PGro...43....1V] [36] Sitzungsberichte der Mathematisch-Physikalischen Classe der Koniglich-¨ Baierische Akademie der Wissenschaften zu Mu¨unchen, Jahrhgang 1920, 87–114. [37] Respectively Astronomische Nachrichten, 213, 45–48 (1921) and 214, 145– 150 (1921). [1921AN....213...45V] and [1921AN....213...45] [38] Astrophysical Journal, 160, 811–830 (1970). [1970ApJ...160..811F]; Astron- omy and Astrophysics, 95, 105–115. (1981). [1981A&A....95..105V] [39] Astrophysical Journal, 303, 556–572. (1986). [1986ApJ...303..556V] [40] Bulletin of the Astronomical Institutes of the Netherlands, 6, 249–287 (1932). [1932BAN.....6..249O] [41] Annals of the New York Academy of Sciences, 198, 255–266 (1972). [1972NYASA.198..255O] [42] The Milky Way Galaxy, IAU Symposium 106, H. van Woerden et al., eds., Dordrecht: Kluwer, 1985) 682 D Notes and References

[43] Beyond the Galaxy: the development of extragalactic astronomy 1885– 1965, Part 1 Journal for the History of Astronomy 39, 91–119 (2008). [2008JHA....39...91] [44] Absorption of light in the Galactic System by Robert J. Trumpler, Robert J., Publications of the Astronomical Society of the Paciﬁc, 42, 214–227 (1930). [1930PASP...42..214T] [45] See Observational evidence conﬁrming Lindblad’s hypothesis of a rotation of the Galactic System by J.H. Oort, Bulletin of the Astronomical Institutes of the Netherlands, 3, 275–282 (1927) and Dynamics of the Galactic system in the vicinity of the Sun, ibid., 4, 269–284 (1928). [1927BAN.....3..275O] and [1928BAN.....4..269O]

Chapter 16. Finale [1] See www.orden-pourlemerite.de. [2] Publications of the Astronomical Society of the Pacific, 30, 331–335 (1918). [1918PASP...30..331M] [3] A full scan of the printed version can be found on my Kapteyn homepage at www.astro.rug.nl/JCKapteyn/Statement USAcad.pdf. [4] De stem van de wetenschap; Geschiedenis van de Koninklijke Nederlandse Academie van Wetenschappen, deel 2, 1914–1918, Amsterdam: Bert Bakker, ISBN 978-90-351-360104 (2011). [5] Als bij toverslag, De reorganisatie van de Leidse 5terrewacht, 1918–1924 and Hij kan toch moeilijk de sterren in de war schoppen. De afwijzing van Pannekoek als adjunct-directeur van de Leidse Sterrewacht. Respectively BMGN/Low Countries Historical Review 120, 207–225 (2005); and Gewina 27, 1–13 (2004). [6] By Anton Pannekoek, B.A. Sijes, E.P.J. van den Heuvel, J.M. Welcker & J.R. van der Leeuw, Amsterdam, van Gennep, (1982). Published posthumously. [7] Publisher was Enschede´ en Zonen, Haarlem (1933). [8] Astronomische Nachrichten, 196, 201–210 (1913). [1913AN....196..201H] [9] Astrophysical Journal, 49, 311–336 (1919). [1919ApJ....49..311S] [10] Preliminary evidence of internal motion in the spiral nebula Messier 101,As- trophysical Journal, 44, 210–228 (1916). [1916ApJ....44..210V] [11] Annals of the New York Academy of Sciences, 198, 255–266 (1972). [1972NYASA.198..255O] [12] Journal for the History of Astronomy, 4, 46–56 and 73–98 (1973). [1973JHA.....4...46B] and [1973JHA.....4...73B] [13] www.beeldbankgroningen.nl/beeldbank/; identificatienummer: NL-GnGRA 1986 1694, Foto M. Th. Koop, collectie RHC Groninger Archieven (1986– 1694). [14] www.beeldbankgroningen.nl/beeldbank/; identificatienummer: NL-GnGRA 1785 7624, Foto P. Kramer, collectie RHC Groninger Archieven (1785–7624). [15] www.beeldbankgroningen.nl/beeldbank/; identificatienummer: NL-GnGRA 1986 1825 and NL-GnGRA 1986 1346, Foto collectie RHC Groninger Archieven (1986–1825 and 1986–1346).1 References 683

[16] Levensverwachting; geslacht en leeftijd, vanaf 1861; statline.cbs.nl/StatWeb/ selection/?DM=SLNL&PA=37450&VW=T. [17] Public Health Reports 84, 661–664 (1969); www.ncbi.nlm.nih.gov/pmc/ articles/PMC2031509/. [18] The Messenger, 67, 62–63 (1992), [1992Msngr..67...62H] [19] See people.physics.tamu.edu/krisciunas/astrs.html. [20] Tijd en toekomst by A.H.P. Luijben & G.J. Kommer, Rijks Instituut voor Volksgezoindheid en Milieu Rapport 270061008 (2010); see www.rivm.nl/ bibliotheek/rapporten/270061008.html. [21] Kluwer (1994), ISBN 0-7923-2979-1. [22] Edited by A. Fowler, London, Imperial College Bookstall. [23] See Report on the Organization of the International Astronomical Union by W.W. Campbell and Joel Stebbins, in: ‘Proceedings of the National Academy of Sciences (USA)’, 6, 349–396 (1920). [www.pnas.org/content/6/6/349.full. pdf+html] [24] Royal Astronomical Society centenary celebrations, 1922 May 29 - June 3, The Observatory, 45, 201–212 (1922). [1922Obs....45..201.] [25] See www.uvm.edu/∼classics/faculty/bach/. [26] Dijksterhuis: een biograﬁe, Bakker, Amsterdam (1996), ISBN 90-351-1694-1. [27] Weekblad voor Gymnasiaal en Middelbaar Onderwijs, 18-e jaargang, N0. 42, 1909–1910.

Appendix A. Publications by and about J.C. Kapteyn, his honors and academic genealogy [1] See adsabs.harvard.edu/abstract service.html, or any other mirror site. [2] See www.dwc.knaw.nl/toegangen/digital-library-knaw/?pagetypepublist&sea¯ rch authorPE00001201¯ . [3] At archive.org/details/copernicus03dubluoft. [4] My Kapteyn Webpage can be found at www.astro.rug.nl/JCKapteyn/ publications. [5] See www.museumboerhaave.nl/Adlib/search/simple, search for ‘Kapteyn’. [6] The NASA Near-Earth Object Project is at neo.jpl.nasa.gov/orbits/. [7] From en.wikipedia.org/wiki/Kapteyn (crater). ‘This ﬁle is made available under the Creative Commons CC0 1.0 Universal Public Domain Dedication.’ [8] See www.rug.nl/corporate/universiteit/luchtfoto. [9] See www.ing.iac.es/PR/. Reproduced with permission. [10] The Websites of the Kapteyn Astronomical Institute are www.rug.nl/ sterrenkunde and www.astro.rug.nl. [11] Vistas in Astronomy, 28, 483–503 (1985). [1985VA.....28..483L]; see also www.ing.iac.es/PR/jkt info/. [12] See www.lorentz.leidenuniv.nl/history/explosion/HKO tree.html. [13] See www-int.stsci.edu/ dejong/stamboom.html. [14] See www.hum.leiden.edu/icd/organisation/members/horstmanshoffhfj.html. [15] See genealogy.math.ndsu.nodak.edu.; Kapteyn is listed as number 112114. [16] Verloren (1997), ISBN 90-6550-543-1. 684 D Notes and References

[17] See Rienhard Klette; www.tcs.auckland.ac.nz/∼rklette/acad ancestors.html. [18] See www.math.uni-leipzig.de/preprint/2007/p1-2007.pdf (p.4). [19] The British Journal for the History of Science, 2, 1–24 (1964). Quote from p.7. [20] Abelard-Schumann (1959), ISBN 0-484-67605-6.

Appendix B. Henriette Hertzsprung-Kapteyn’s biography of J.C. Kapteyn [1] See www.dbnl.org/tekst/hert042jcka01 01/, where versions in .jpg and .txt formats are provided. [2] See for example as www.genealogieonline.nl/genealogie-baert-cornelis-kals hoven/I225.php, www.middel.org/canon-van-groningen/kapteyn and www. lamartin.com/genealogy/kalshoven.htm. [3] The Website is www.allegroningers.nl. [4] Groninger Historische Reeks (1998). [5] See www.allegroningers.nl, Geboorteregister Groningen 1881, Aktenummer 1429. [6] Berlin, Springer (1994) ISBN 3-540-56788-6. [7] See www.allegroningers.nl, Huwelijksregister Groningen 1913, Aktenummer 210. [8] My ﬁrst 72 years of astronomical research. Reminiscences of an astronomical curmudgeon, revealing the presence of human nature in science. Privately published by Willem J. Luyten, 1940 East River Road, Minneapolis, MN 55414, USA. 20+203 pp. (1987). [1987fsya.book.....L] [9] See www.online-begraafplaatsen.nl/zerken.asp?command=showgraf&graﬁd= 200874. [10] The Legacy, pages 38–40. [11] Private communication in this paragraph from Jan Willem Noordenbos, great- grandson of Kapteyn, who remembered ‘Aunt Rigel’ well. [12] Space Science Reviews, 64, 1–92 (1993) (with a preface and introduction on pp. x-xix) [13] Kluwer (1993), ISBN 978-07-923-2603-8. [14] The Observatory, 115, 284–5 (1995). [1995Obs...115..284J] [15] See www.astro.rug.nl/JCKapteyn; the URL of the English translation is www. astro.rug.nl/JCKapteyn/HHKbiog.pdf.

Appendix C. Cornelius Easton: Personal memories of J.C. Kapteyn [1] The URL is www.astro.rug.nl/JCKapteyn/Easton.pdf. [2] See www.readbookonline.net/readOnLine/20049/. [3] Astrophysical Journal, 37, 105–118 (1913). [1913ApJ....37..105E]. [4] See hdl.huntington.org/cdm/singleitem/collection/p15150coll2/id/569/rec/3. Index

Symbols altitude, 64, 77, 126 α Centauri, 135, 139, 354 American Philosophical Society, 631 δ Cephei, 590, 592 American Society, 631 ω Centauri, 245, 246 Anderson, Thomas David, 311 100-inch telescope (Mount Wilson), 458, 459 Andree´ Wiltens, Albert John, 32 1882, Great comet of, 154, 157, 158 Andree´ Wiltens, Elisabeth Henriette, 108 60-inch telescope (Mount Wilson), 375, 376, Andree´ Wiltens, Henry Maximiliaan, 32, 109 378, 455, 457, 458, 460, 463, 465, 468, Andree´ Wiltens, Henry William, 32, 108 482, 488, 548 Andree´ Wiltens, Jacob Willem Gerard 61 Cygni, 139, 252–254, 260 Hendrik, 32 Andree´ Wiltens, Maximiliaan Leonard, 32 A Andromeda Nebula, 208, 294, 404 Abbot, Charles Greeley, 468, 485 Angstr˚ om,¨ Anders Jonas, 530 aberration of light, 66, 67, 74, 128, 236 Ankara Observatory, 558 Absolute Magnitude, 46, 327 annual parallax, 138 definition, 326–328, 558, 605 anomalistic month, 124 absorption of light, see extinction, interstellar Antapex, 291 Academic Statute, 88 Apex, see Solar Apex Academie´ des Sciences, 185, 630, 631 apparent magnitude, 46 Academy Building, 62, 86, 92, 98, 518–520 Arago, François Jean Dominique, 46 actinometer, 414 Argelander, Friedrich Wilhelm August, 74, 75, Adams, Walter Sydney, 368, 376, 454, 468, 155, 163, 231, 321, 351, 436, 523, 570 484, 485, 487, 495, 496, 533, 542–555, Arminius, Jacobus, 90 557, 599, 622, 645 Ascension (island), 81 Aethra (minor planet), 117 Astrographic Catalogue, 194, 196, 249, 397, airglow, 438 489 Airy, George Biddell, 48, 53, 81, 196, 234, 236, Astronomical Journal, 118, 478 321, 323, 324, 436 Astronomical Laboratory Kapteyn, 589 Albany Observatory, 471 Astronomical Society of the Atlantic, 353, 362, Aldebaran, 384, 385 587 Alexander von Humbold Stiftug, 200 Astronomical Society of the Pacific, 203, 493, Algol (β Persei), 581 630 Allebe,´ Gerardus Arnoldus Nicolaus, 149, 150 Astronomische Gesellschaft, 68, 75, 575, 576 Allegheny Observatory, 471, 487, 491 Astronomische Gesellschaft Katalog (AGK), Almagest, 74 75, 78, 156, 231, 523

Astronomische Nachrichten, 118 Bijlsma, Dirk Klazes, 100 Astronomisches Rechen-Institut (Berlin), 62 binary star, 67, 76 Asymmetric Drift, 552, 554 Blaauw, Adriaan, v, ix, x, xii, xiii, xvii, 204, Ausfeld, Hermann, 73 369, 371, 372, 377, 379, 380, 420, 579, Auwers, see von Auwers 580, 604, 621, 628, 629, 643, 647–648, Auwers-Bradley stars, 74, 295, 321, 322, 326, 664 327, 342, 343 Black Hole, 209 azimuth, 64, 77, 126 blackboard globes, 420, 542, 543 Boer wars, 274 B Boerhaave, Herman, 28 Baade, Wilhelm Heinrich Walter, 378, 380, Boissevain, Ursul Philip, 56, 266, 423, 475, 592 577, 630 Baart de la Faille, Jacob, 90, 91, 277 Bok globule, 402 Babcock, Harold Delos, 454, 468, 488 Bok, Bartholomeus Jan, 377, 628 Bach, Johann Sebastian, 608 Bolland, Gerardus Johannes Petrus Josephus, Backlund, Jons¨ Oskar, 336, 345, 353 425 Bacon, Francis, 425 Boltzmann, Ludwig Eduard, 366 Bacon, Roger, 27 Bonn Observatory, 75, 96, 155, 231, 362, 367, Baillaud, Edouard-Benjamin, 604, 606 376, 387, 408, 487 Baillaud, Jules, 576 Bonner Durchmusterung, 74, 75, 155, 163, Bakhuyzen, see van de Sande Bakhuyzen 286, 523 Barnard 68 (dark cloud), 402, 403 Bordewijk, Hugo Willem Constantijn, 593, Barnard’s Loop, 399, 401 608 Barnard’s Star, 238 Bos, Pieter Roelf, 281 Barnard, Edward Emerson, 238, 407, 475 Boss, Benjamin, 478 Barneveld, 1–18 Boss, Lewis, 146, 324, 336, 343, 388, 389, 478, Barnouw, Adriaan Jacob, 646 542, 600, 605, 613, 624 Bartsch, Jacob, 638 Boswell, James, 425 Batavia (Jakarta), 59 Bouquet de La Grye, Jean Jacques Anatole, Batavian Society for Experimental Philosophy 189 (Rotterdam), 168, 631 Boveri, Theodore Heinrich, 477 Battista, Orlando Aloysius, 1 Boyden Station, 369 Bauschinger, Julius, 62 Boyden, Uriah Atherton, 369 Becker, Ernst Emil Hugo, 96 Bradley, James, 67, 74, 295, 299, 300, 318, Becker, Wilhelm, 377 616, 617 Benno, 5, 9–12, 14, 21, 22, 633, 635 Brandt, Catharina Elisabeth, 6 observatory, 22 Bergedorfer Spektral-Durchmusterung, 377, Bravais, Auguste, 292, 300, 322, 324, 388, 408, 379, 381 435, 514, 626 Bergedorfer Sternwarte, see Hamburg Bravais, Louis Franc¸ois, 292 Observatory British Association (for the Advancement of Berlage, Hendrik Petrus, 304 Science), 184, 297, 342, 353, 515, 631 Berlin (Babelsberg) Observatory, 74, 95, 96, British Society, 298 295, 376 Broerstraat, 419 Berlin Academy, 187, 190 Brouwer, Hendrik Albertus, 268 Bernoulli, Daniel, 28, 40, 637 Brouwer, Seerp, 91 Bernoulli, Jacob, 637 Brouwer, Simon, 49, 108 Bernoulli, Jacob (II), 39, 40 Bruce Medal, 203, 493, 630 Bernoulli, Johann, 28, 91, 637 Br¨uck, Hermann Alexander, 377 Berra, Yogi (Lawrence Peter), 27, 661 Brugmans, Antonius, 29, 637 Bessel, Friedrich Wilhelm, 74, 139, 216, 295 Bruno, Giordano, 221 Bethe, Hans Albrecht, 270 Bulletin Astronomique, 118 Bible Belt, 3 Burck, William, 81, 108 Big Dipper, 46 Bussy-Rabutin, Roger, xiv Index 687

Buys Ballot, Christophorus Henricus Dider- Copenhagen Observatory, 491, 533, 547, 575, icus, 29–31, 36, 37, 39, 41, 58, 71, 93, 642 122, 284 Copernicus (journal), 116, 118, 126, 131 Copernicus, Nicolaus, 74, 91, 263 C Cordoba´ Durchmusterung, 74, 156, 238, 240, Calvinism, 90 285 Campbell, William Wallace, 301, 337, 338, Cordoba´ Observatory, 195, 231, 376 487, 530, 533, 541, 545, 551, 587 Corneille, Pierre, 12 Camper, Petrus, 86, 518, 520 Cort van der Linden, Pieter Willem Adriaan, Cannon, Annie Jump, 289 584 Cape Observatory, see Royal Observatory, Coude´ focus, 490 Cape of Good Hope Coude´ spectrograph, 530 Cape Photographic Durchmusterung, 156–204, Couderc, Paul, 314 223, 246, 612, 615, 616, 618, 631 Courvoisier, Leopold, 137 Capteyn, Paulus, 6 Cruls, Lu´ıs Ferdinand, 189 Carbon star, 533 Crux (constellation), 354 Carnegie Institution, 365, 454, 458 Curtis, Heber Doust, 567, 592 Carnegie, Andrew, 365, 454 Cushing, Harvey William, 588 Carte du Ciel, 119, 184–196, 223, 225, 226, 230, 233, 247, 249, 250, 255, 269, 270, D 375, 397, 446, 489, 523 Daguerre, Louis Jacques Mande,´ 154 Cassegrain focus, 490, 531 daguerreotype, 154 Cassini, Giovanni Domenico, 221 Dartmouth College, 531 Cassiopeia, 46 Darwin, Charles Robert, 30, 110, 231, 510, 570 Catalogue of Nebulae and Clusters, 403 Daudet, Alphonse, 25 Cauchy, Augustin Louis, 39, 40, 476 de Boer, Floris, 88, 433 celestial sphere, 64 de Boer, Petrus, 88 Celsius, Anders, 190 de Cock, Hendrik, 15 Center for High Angular Resolution de Genestet, Petrus Augustus, 10 Astronomy, 473 de la Fontaine, Jean, 652 Centre de Donnees´ Astronomiques, 669 de la Rochefoucauld, Franc¸ois, 659 Cepheid, 372, 566, 590 de Rabertin, Roger, 496 Ceres, 38 de Rabutin, Roger, xiv Chandler, Seth Carlo, 478 de Sitter, Aernout, ix, 628 charge-coupled device (CCD), 153 de Sitter, Willem, vii–ix, 3, 138, 201, 233, 244, Chladni, Ernst Florens Friedrich, 39, 40 246, 256–261, 282, 287–288, 305, 309, Christ, Jesus, 3 353, 372, 379, 385, 387, 434, 445–448, Christie, William Henry Mahoney, 187, 190, 500, 538, 577, 581–586, 597, 604–606, 192, 193, 196–198, 202, 203 616, 618–620, 625–629, 645, 646 Cincinnati Observatory, 322 de Sitter, Wolter Reinold, 581 Clerke, Agnes Mary, 205, 238, 293 de Vos van Steenwijk, Jacob Evert (Baron), Coalsack, 354, 362, 402 605 coelostat, 458 de Vries, Hugo, 344, 507 Cohn, Fritz, 617 de Vries, Teunis Willem, 170, 173, 216, 260, comet, 38 371, 582 Comstock, George Cary, 146, 336, 339, 362, de Zoute, J.M., 371, 372 391, 394, 395, 397, 479 declination, 63, 64, 126 Conference´ Gen´ erale´ des Poids et Mesures, Dekking, Willem, 597 190 Delambre, Jean-Baptiste Joseph, 29 Congress of Vienna, 28 Descartes, Rene,´ 524 Convention du Metre,´ 190 DeVorkin, David Hyam, x, 490, 547, 555 Cook, Frederick Albert, 511 Dickens, Charles, 110, 652, 653 Cookson, Bryan, 257, 353 Dijksterhuis Eduard Jan, 609 Copeland, Ralph, 118 disk, 210 688 Index

Domela Nieuwenhuis, Ferdinand, 204 equatorial mount, 66 Donders, Franciscus Cornelis, 30 equinox, 64, 74 Donner, Anders Severin, 187, 188, 217, Eratosthenes of Cyrene, 60 233, 248–253, 260, 269, 302, 353, 359, Ermerins, Jan Willem, 92 364, 384, 385, 387, 490, 514, 538, 577, Escher, Maurits Cornelis, 205 616–620 European Southern Observatory, 208, 354, Doppler, Christian Andreas, 41, 284, 531 400, 402, 671 Dorpat Observatory, 139 European Space Agency, 196, 384, 390 double refraction, 47 extinction, interstellar, 216, 300, 339, 391–392, Downing, Arthur Matthew Weld, 81 403, 563, 566–568, 590 draconic month, 124 Eyjafjallajokull¨ volcano, xvii Draper Catalogue, 289, 296, 324, 411, 420, 548 Draper, Henry, 154, 289 F Draper, John William, 110 Fahrenheit, Daniel Gabriel, 191 Dreyer, John Louis Emil, 118 Fath, Edward Arthur, 468, 488 Dubois, Eugene,` 283 Faye (comet), 117 Dudley Observatory, 146, 324, 336, 388, 478 Faye, Herve,´ 189, 192 Dun Echt Observatory, 118, 131 Feast, Michael, 163, 166, 196, 257, 259, 379 Dunsink Observatory, 118 Fechner, Gustav Theodor, 510 Durchmusterung, 74 Ferwerda, Jacobus Gijsbertus, 628 dynamic range, 154 Feynman, Richard Phillips, 501 Dyson, Frank Watson, 342, 357, 359, 368, 587, Finlay, William Henry, 135, 258, 626 588 Finnish Academy of Sciences, 631 Firework nebula, 315 E Fleming, Williamina Paton Stevens, 237, 289, Eastman, George, 154 484, 615 Eastman, John Robie, 80 Flint, Albert Stowell, 146, 300, 325 Eastman-Kodak Company, 154 Flourens, Emile,´ 192 Easton, Cornelis, x, 56, 122, 262, 303, Flower Observatory, 270 404–407, 625, 626, 651–660 Flower, Reese Wall, 270 Eberhard, Gustav Edward, 586, 594 Forster, John, 652 eccentric anomaly, 112 Foucault, Jean Bernard Lon,´ 309 Eckermann, Johann Peter, 652 France, Anatole, 351 ecliptic, 64 Franklin-Adams, John, 652 ecliptic latitude, 64 Freeman, Kenneth Charles, 565 ecliptic longitude, 64 Fresnel, Augustin-Jean, 46 Ecole´ Polytechnique (Paris), 25, 40 Frieseman, H.M.A.A., see Kalshoven– Eddington, Arthur Stanley, 1, 204, 342, 356, Frieseman, Henriette¨ Mariette¨ Augustine 357, 416, 418, 459, 471, 500, 537, 541, Albertine 555, 563, 567, 568, 573, 576, 587 Frost, Edwin Brant, 362, 365, 366, 471, 482, Eddington, Arthus Stanley, 343 486, 487, 491, 530, 531, 572, 620 Edgeworth, Francis Ysidro, 510 Fundamental Catalog, 63, 74, 76 Eecen, Adrianus, 69, 73 Ehrenfest, Paul, 425, 526 G Eighty Years War, 86 GAIA satellite, 390 Eijkman, Johan Fredrik, 281 Galactic disk, 209, 244 Einstein, Albert, vii, xi, 312, 424, 576, 583, Galactic equator, 64 608, 642 Galactic halo, 209, 210, 244, 246 Elkin, William Lewis, 135 Galactic latitude, 64 elliptical galaxy, 211 Galactic longitude, 64 Emma, Queen-regent of the Netherlands, 218, galaxy, 210 226 classiﬁcation, 211 Emmius, Ubbo, 86, 90 formation, 210 Enschede,´ Willem Adriaan, 71, 92, 93, 96, 106 Galilean satellites (Jupiter), 258 Index 689

Galilei, Galileo, 74, 211, 258 Harting, Pieter, 30 Galle, Johann Gottfried, 38 Harvard College Observatory, 48, 144, 194, Galton, Francis, 506, 509, 510, 513, 514 229, 289, 302, 336, 362, 368–370, 376, Gauss, Johann Carl Friedrich, 322 377, 454, 465, 471, 478, 483, 495, 548 Gautama Siddhartha, 111 Harvard Map of the Sky, 539 Geertsema, Carel Coenraad, 226 Harvard Northern Durchmusterung, 495 Georgia State University, 473 Harvard University, 270, 630 Germain, Marie-Sophie, 39, 40 Harvard-Groningen Durchmusterung, Giant Molecular Clouds, 532 369–375, 377, 489, 560 Gill, David, ix, 81, 126, 131–137, 145, 147, Hassler, Ferdinand Rudolph, 345 154–204, 223, 224, 231, 236–244, Hassler, Mary Caroline, 274, 345, 469, 471, 246–248, 258, 269, 271, 272, 275, 286, 480 297, 302, 305, 337, 352, 353, 355, 360, Havank (Hendrikus Frederikus van der 362, 364, 367, 368, 447, 448, 463, 471, Kallen), 263 480, 491, 497, 515, 516, 570, 578, 579, Hearn, Patrick Lafcadio, 311 612, 613, 615, 616, 618, 622, 626 Hegel, Georg Wilhelm Friedrich, 387 Gill, Isobel S., 577 heliometer, 67, 135, 139, 160 Gingerich, Owen, 327, 547, 555 helium burning, 207 Glaisher, James Whitbread Lee, 351 helium stars, 486 Gleuns Jr., Willem, 280 Helmert, Friedrich Robert, 235 Gleuns, Willem, 70, 280 Helsingfors Observatory, 187, 217, 249, 251, globular cluster, 209, 244–246, 415, 590, 591 252, 300, 386, 388, 538 Goethe, see von Goethe Hemel & Dampkring, 122, 302, 350, 629, 630, Gold Medal Royal Astronomical Society, 203, 651 351, 630 Henderson, Thomas James, 139 Golius, Jacobus, 59 Henry Draper Catalogue, 144 Gomarus, Franciscus, 90 Henry, Mathieu-Prosper, 158, 185, 187, 193, Gotha Observatory, 73 194, 222, 237, 497 Grinwis, Cornelis Hubertus Carolus, 25, Henry, Paul-Pierre, 158, 185, 187, 194, 222, 29–31, 34, 39, 58, 71, 93, 97, 636 237, 497 Groneman, Florentius Goswin, 146, 277, 278 Herrmann, Dieter Bernhard, 598, 601, 643 Groneman, Hendrik Jan Herman, 146 Herschel, Caroline Lucretia, 211, 231 Groningen, city of, 85 Herschel, Frederick William, 38, 205, 211, Groombridge, Stephen, 259, 357 212, 214, 215, 231, 263, 291, 315, 352, Grubb, Howard, 194 363, 391, 397, 403, 428, 653 Gunning, Johannus Hermanus, 10 20-foot telescope, 211, 215 40-foot telescope, 212, 213, 215 H Construction of the Heavens, 213 handχ Persei, 259 equalisation of starlight, 214 Haga, Hermanus, 226, 252, 434 limiting magnitude, 214 Hagen, Johann Georg, 397 star counts, 212 Hale, George Ellery, 5, 118, 302, 336, 344, Herschel, John Frederick William, 46, 212, 364–368, 375, 453–500, 517, 519–527, 231, 352, 391, 397, 402, 403, 414, 653 531, 562, 577, 581, 587, 599, 602, 608, Hertzsprung, Ejnar, 5, 149, 206, 233, 283, 379, 642, 645–647 490, 491, 493, 494, 545, 547, 549, 551, Hale, William Ellery, 458 558, 566, 583–585, 590, 592, 598, 605, Hall, Asaph, 146 628, 640–644 Halley’s comet, 38, 61 Hertzsprung, Rigel, 5, 527, 597, 598, 643, 646 Halley, Edmond, 38, 139, 221 Hertzsprung–Russell diagram, 206, 207, 288, Hamburg Observatory, 376, 490 410, 547, 548, 642 Hamburger, Hartog Jacob, 171, 279, 418 Hertzsprung-Kapteyn, see Kapteyn, Henriette Hamerling, Robert, 26 Mariette Augustine Albertine Hamilton, James, 202 Heymans, Gerardus, 56, 279, 303, 387, 423, Harmonie, de (concert hall), 102, 426, 427, 608 424, 510, 524, 526, 573, 574, 577, 643 690 Index

Heynsius, Adriaan, 10 International Association of Academies, 574 Hiemstra, Broer, 628 International Astronomical Union, 574 Hill, Octavia, 480, 481 International Astronomical Union (IAU), 327, Hilversum, 5 369, 381, 603, 604 Hinks, Arthur Robert, 314, 342, 353, 354, 587 International Council for Science, 574 Hins, Coert Hendrik, 628 International Council of Scientific Unions, 574 Hipparchus of Nicaea, 64, 74 International Research Council, 573, 574, 576 Hipparcos, 144, 196, 292, 384, 388, 390 interstellar absorption, see extinction, Hoek, Martinus, 37, 39, 62 interstellar Hoek, Paulus Peronius Cato, 81 interstellar reddening, see extinction, Hohwü, Andreas, 68 interstellar Holland Society of Sciences and Humanities, Isaac Newton Telescope, 633 631 Holleman, Arnold Frederik, 282 J Holmes, Oliver Wendell, 273 Jackson, Jesse Louis, 1 Holwerda, Allard Othumar, 626 Jacobs, Aletta Henriette,¨ 303 Hondsrug, 85 Jacobus Kapteyn Telescope, 633, 635 Hoogere Burgerschool, 62, 71, 108, 146, 264, James Clerk Maxwell, 131 277, 557 James Ludovic Lindsay, 118, 131 Hook and Cod Wars, 4 Janssen, Pierre Jules Cesar,´ 192 Hooker, John Daggett, 458 Jeans mass, 532 Hopmann, Josef, 624 Jeans, James, 98, 532, 567, 608, 625 Horrebow, Peder, 128 Johns Hopkins University, 270 Horrebow-Talcott method, 128, 130 Jones, Derek, 649 Horsehead nebula, 401 Jost, Ernst Heinrich Rudolph, 300 Hotel De Doelen, 594–596 Joy, Alfred Harrison, 553 hour angle, 126 Joyner, Mary Cross, 488, 624 Hubble classification, 211 Juliana, Queen of the Netherlands, 276 Hubble, Edwin Powell, 211, 378 Julius, Willem Henri, 366, 458, 482, 483 Hubrecht, Ambrosius Arnold Willem, 81, 82, Juno (minor planet), 117 97, 571 Jupiter, 154 Hubrecht, Jan Bastiaan, 570 Hudig, Johanna Clementina, 645 K Hudig, Joost, 149, 283, 426, 644, 645 Konig,¨ Johann Samuel, 28 Hudig, Sophia Alida, 645 Kaiser, Frederik, 37, 60–68, 225 Huggins, William, 198, 367, 404 Kalshoven, Catharina Elisabeth, x, 5, 6, 25, Huizinga, Dirk, viii, 171, 223, 226, 233, 281, 49–660 282, 418 Kalshoven, Catherina Elisabeth, 272 Huizinga, Johan, vii–ix, 1, 645, 646 Kalshoven, Jacobus Wilhelmus, 49 Humason, Milton Lasell, 376 Kalshoven, Jacobus Wilhelmus (Jacques), 50, Huygens, Christiaan, 38, 47 52, 108 Hyades, 252, 269, 318, 359, 384, 385, 387, Kalshoven, Jacqueline Wilhelmine, 49, 107 388, 460, 495, 548, 618 Kalshoven, Johan Christaan, 108 hydrogen burning, 206 Kalshoven, Maria Gabrielle, 50 Kalshoven, Marie Gabrielle, 50, 148 I Kalshoven–Frieseman, Henriette¨ Mariette¨ Ilcken, Ada Christina Mathilde, 14 Augustine Albertine, 6, 49–52 Imperial Academy of St. Petersburg, 631 Kam, Nicolaas Mattheus, 62 Innes, Robert Thorburn Ayton, 203, 238–244, Kamerlingh Onnes, Heike, 34, 106, 540 258, 287, 577 Kapteyn Innes, Robert Thorburn Ayton, 595, 618 spelling of name, 641 Instituto de Astrof´ısica de Canarias, 633 Kapteyn (crater), 632, 633 Interallied Association of Academies, 574 Kapteyn Astronomical Institute, ix, 21, 279, intermediate dispersion spectrograph, 531 632, 634 Index 691

Kapteyn Astronomical Laboratory, 589 definition of absolute magnitude, 326, 327, Kapteyn Cottage, 473–475 338, 605 Kapteyn Fund, 597 fatal illness, 603 Kapteyn Group, 245, 246 Gold Medal Royal Astronomical Society, Kapteyn homes 351, 630 Eemskanaal, 98, 266, 348, 480 height, 56, 652 Grote Markt, 98, 594–596 inaugural lecture, 33, 99, 100, 102 Heerestraat, 98, 152, 266, 346, 347, 424, 653 marriage, 107 Hilversum, 593, 602 marriage certificate, 107–109 Hotel de Doelen, 593, 601 military service, 53 Oosterhaven, 98, 266, 480 Natuurkundig Genootschap, 276–284 Oosterstraat, 98, 151, 421 Orden Pour le Merite,´ 569–571, 587 Ossenmarkt, xiv, 98, 348, 349, 428, 593, PhD thesis, 34, 41–49, 58 653, 660 portrets, 420, 578–580 Peperstraat, 97, 98 Rector Magnificus, 218, 220 Vries, 265, 472, 480 resigns from Royal Academy, 574 Winschoterkade, 98, 105, 106, 148, 151 retirement, 601 Royal distinctions, 569, 571, 630, 657 Kapteyn Lounge, 279, 283 spelling of name, 18, 641 Kapteyn Room, ix, x, 21, 122, 141, 230, 279, star map, 21 420, 422, 612, 614, 621, 629 statistics, 505–516 Kapteyn’s Star, 238–246, 615, 631 teacher, 429–434 Kapteyn, Adriaan Pieter Marinus, 16, 17, 107 tides, 501–504 Kapteyn, Agatha, 16 tree rings, 122–126 Kapteyn, Albertina Maria, 20, 104, 107, 144, women rights, 303 200 Kapteyn, Johannes Catharinus, 16 Kapteyn, Albertus Philippus, 17 Kapteyn, Machtelina Elisabeth, 16 Kapteyn, Cornelia Louise Alexandra, 16, 104, Kapteyn, Maria Adriana, 16 106, 107 Kapteyn, Marius, 16 Kapteyn, Frederik Willem Hendrik, 641, 643 Kapteyn, Nicolaas Pieter, 16, 30, 31, 34, 35 Kapteyn, Gerrit Jacobus, 5–14, 21, 22, 107, Kapteyn, Paulus Huibert, 16 110, 151, 307, 639, 654, 656 Kapteyn, Willem, 30, 31, 34, 35, 39–41, 82, 83, Kapteyn, Gerrit Jacobus (son), 148, 298, 303, 118, 121, 147, 317, 538, 612, 616, 619, 306, 307, 347, 466, 467, 480, 502, 609, 626 610 Kapteyn-Kalshoven, see Kalshoven, Catharina Kapteyn, Henriette Mariette Augustine Elisabeth Albertine, viii, 5, 148, 151, 202, 206, Kapteyn-Koomans, see Koomans, Elisabeth 298, 303, 347, 481, 492, 526, 585, 607, Cornelia 625, 639–641 Kapteynborg, 632–634 first name, 639 Kapteynia, 632 marriage to Hertzsprung, 494, 642–644 Kapteynstraat, 633, 635 marriage to Hudig, 644, 645 Karslruhe, Sternwarte, 318 Kapteyn, Huibert Paulus, 16, 22 Keats, John, 428 Kapteyn, Jacoba Cornelia, 148–150, 202, 264, Keeler, James Edward, 118 298, 303, 347, 480, 579, 588, 597, 609, Kelvin, Lord (William Thomson), 270 610, 630, 639 Kempf, Paul Friedrich Ferdinand, 296, 301 Kapteyn, Jacoba Cornelia (Aunt Ko), 18 Kepler’s equation, 112–119, 121, 147 Kapteyn, Jacobus Cornelius, 1–660 Kepler’s laws, 113 70th birthday, 586, 588 Kepler, Johannes, 28, 74, 85, 112, 392, 612, birth certificate, 19 638 brothers and sisters, 16, 17, 19 Keunen, Johannes Petrus, 445 Bruce Medal, 630 Keyser, Jan Frederik, 61 children, 149 Kinman, Thomas D., 376, 378 church wedding, 106 Kirchhoff, Gustav Robert, 39, 40 692 Index

Kladboeken, ix, 372 Liccione, Anthony, 383 Klein Wassink, Willem Jan, 627 Lick Observatory, 312, 313, 337, 376, 487, Kluyver, Jan Cornelis, 445 533, 551, 680 Knipperdolling, Bernhard, 26 light-year, 139 Kobold, Hermann Albert, 322 Lindblad, Bertil, 554, 567, 568 Kohlsch¨utter, Ernst Arnold, 490, 500, 519, Lindsay, James Ludovic, 202 544–552, 557 lines of nodes, 42 Konig,¨ Johann Samuel, 637 Linnæus, Carl Nilsson, 28 Konigsberg¨ Observatory, 139 Liouville, Joseph, 300, 435 Konigstuhl¨ Observatory, 96, 632 Littrow, see von Littrow Koninklijk Natuurkundig Genootschap Lixk Observatory, 592 (KNG), see Natuurkundig Genootschap Local Standard of Rest, 139, 290, 291, 295, (Groningen) 315 Koninlijke Academie van Kunsten en Lockyer, Joseph Norman, 367 Wetenschappen (KNAW), see Royal Lœwy, Maurice, 193 Netherlands Academy of Arts and log-normal probability distribution function, Sciences (KNAW) 505 Koomans, Elisabeth Cornelia, 5, 8–14, 107 Lord Kelvin, see Thomson, William Korteweg, Diederik Johannes, 573 Lord Rayleigh, see Strutt, John William Kostinsky, Sergej Konstantinovich, 300, 490, Lord Rosse, see Parson, William 538 Lorentz, Hendrik Antoon, 34, 492, 525, 526, Kreiken Observatory, 558 570, 574, 575, 656 Kreiken, Egbert Adriaan, 14, 557, 582, 627 Louisiana Purchase Exposition, 333 Kreiken, Willem Rudolph, 14 luminosity curve, 559 Krul, Wessel, 101, 104, 112, 204, 220, 302, Lunar eclipse, 75, 124 304, 307 Lunar occultation, 75, 78 Kuiler, Kor, 608 Lund Observatory, 439, 539 Kuiper, Gerrit Pieter, 628 Lusitania, 521, 571, 587 K¨ustner, Karl Friedrich, 362, 367, 368, 387, Luyten, Willem Jacob, 628, 644 389, 487, 577, 587, 620 M L M101, 210, 404–406, 525, 591 La Plata Observatory, 376 M51, 404–406 La Silla Observatory, 400 Macpherson, Hector Carsewell, 342 Lagrange, Joseph-Louis, 39, 114 Magellanic Clouds, 208, 438, 439 Lame,´ Gabriel Leon´ Jean Baptiste, 41, 45 magnitude, 46 Laplace, Pierre-Simon, Marquis de, 503 absolute, 46, 327, 559 Law on Higher Education of 1876, 87–89 apparent, 46 le Verrier, Urbain, 38 Main Sequence, 206, 312 League of Nations, 572, 576 Mannheim Observatory, 69, 95, 96 Leavitt, Henrietta Swan, 372, 590 Mars, 76, 79, 131, 612 Lecointe, George, 576 Martin, Willem Christiaan, 628 Legendre, Adrien-Marie, 322 Massachusetts Institute of Technology, 527 Legion´ d’Honneur, 571 Mathieu, Emile´ Leonard,´ 41 Leibniz, see von Leibniz Maury, Antonia Caetana de Paiva Pereira, 289, Leiden Observatory, 58–81, 96, 100, 121, 197, 410, 547 225, 231, 248, 252, 258, 338, 355, 357, Maxwell, James Clerk, 358 371, 376, 386, 406, 444–449, 469, 491, Mayer, Christian, 221 539, 562, 575, 582, 588, 600, 606 McAldie, Alexander George, 125 reorganisation, 581–584 McGee-Newcomb, Anita, 345 specializes in everything, 584 Mees, Rudolf Adriaan, 71, 91, 92, 106 Leiden University, 27, 59, 61, 203 Meijer, Johan Hendrik, 10 Lembang Observatory, ix, 14, 558 Meijering, Samuel¨ Cornelis, 541, 622, 626 Lessing, Gotthold Ephraim, 12, 25, 426, 660 meridian circle, 65, 66, 68, 77, 142 Index 693

Mesdag, Ferdinand Taco, 502 neutron star, 209 Messier Catalogue, 294, 400, 403, 404 New–England Magazine, 273 Messier, Charles, 403 Newcomb (McGee), Anita, 345 Meudon Observatory, 192 Newcomb, Simon, xiii, 53, 74, 137, 221, Michelson, Albert Abraham, 38 269–274, 286, 296, 297, 300, 322, 333, Michelson-Morley experiment, 38 335, 344, 361, 404, 439, 463, 467, 469, Milky Way, 209 471, 570, 612 Milky Way Galaxy, 209 Newcomb-Hassler, Mary Caroline, see Hassler, Milton Lasell Humason, 376, 488 Mary Caroline minor planet, 37, 38, 62 Newton, Isaac, 42, 113, 425, 453, 503, 564, Modderman, Hendrik Jacob Herman, 277 638 Modderman, Rudolph Sicco Tjaden, 277 Newtonian focus, 490 Molengraaff, Adolf Frederik, 268, 577 NGC6744, 210 Moliere` (Jean-Baptiste Poquelin), 12 NGC891, 210, 403 Moll, Gerard (Gerrit), 29, 36, 61, 62, 509, 636 Nijland, Albertus Antonie, 170, 434, 490, 538, Moll, Jan Willem, 507, 508, 577 539, 584, 597, 605, 626, 660 Monastery (Mount Wilson), 465, 662 Nolst Trenite,´ Jean Ged´ eon´ Lambertus, 107 Monck, William Henry Stanley, 294, 541 Noordenbos, Greta, 298, 589, 609, 610 Monnichmeyer,¨ Carl Otto Louis, 408, 624 Noordenbos, Jan Willem, xvi, xvii, 589, 609, Moon, 75 610 Morley, Edward Williams,, 38 Noordenbos, Willem, 579, 588, 602, 603 Mouchez, Ernest Amed´ ee´ Barthelemy,´ 157, Noordenbos, Willem Cornelis, 149, 298, 480, 158, 184–193, 497 597, 609, 610, 643 Moulton, Forest Ray, 481 normal probability distribution function, 505, Mount Wilson Catalogue, 375, 378, 487–489, 506 560 Nort, Isidore Henri, 539, 626 Mount Wilson Observatory, x, 302, 365, 367, North Polar Sequence, 370, 375, 488 376, 378, 414, 415, 453, 455–500, 540, nova, 237, 312 545–555, 592, 644, 653, 662 Nova Persei, 284, 311–315, 616, 618 Mount Wilson Toll Road, 453, 464 Noyes, Arthur Amos, 527 moving cluster method, 388 nucleosynthesis, 209, 210 Muir, John, 311 nutation, 64, 74 Mulder, Gerardus Johannes, 30 Mulerius, Nicolaus, 89 O Müller, Karl Hermann Gustav, 241 O’Grady Marcella, 477 Müller, Philipp, 638 objective prism, 376, 414 Multatuli (Eduard Douwes Dekker), 45, 110 obliquity of the ecliptic, 64 München Observatory, 96, 576 observator, 61 Observatorio del Roque de los Muchachos, N 633 Napoleon (Bonaparte), 28 ObservattoiredeParis,see Paris Observatory National Academy of Arts and Sciences (US), Occam’s Razor, 416 365, 367, 517, 521, 606, 631 Olbers paradox, 392 National Academy of Sciences (US), 493, 494 Olbers, Heinrich Wilhelm, 392 Natuurkundig Genootschap (Groningen), 104, Ommelanden, 86 146, 276–284, 512, 633, 659 Oort, Jan Hendrik, 138, 233, 244, 359, 374, scientific chapter, 281 379, 380, 431, 554, 565, 567, 568, 584, scientific department, 645 591, 627, 628, 636 Natuurkundig Gezelschap (Utrecht), 29 Oosterhoff, Pieter Theodorus, 628 Nautical Almanac Office, 270 Oppolzer, see von Oppolzer Nederlandsch Natuur- en Geneeskundig opposition, 76 Congres, 284 Orange Free State, 274 Nederlandse Astronomen Club, 660 Orden Pour le Merite,´ 569–571 Neptune, 38 Order of Oranje-Nassau, 571, 657 694 Index

Order of the Dutch Lion, 571, 657 Pickering, Edward Charles, 194, 237, 289, 302, Organiek Besluit of 1815, 28, 87 336, 352, 362, 368, 369, 372, 375, 390, Orion, 46, 399, 401, 486 392, 394, 395, 397, 410, 411, 454, 482, Orion Nebula, 154, 208, 215, 362, 399, 400, 484, 487, 495, 539, 547, 570, 577, 612, 404, 544 622, 624 Orion stars, 486 Pinwheel galaxy, 404–406, 525, 536, 591 ornithology, 654 Pioneer 10/11, 438, 440 Osborn, Henry Fairfield, 468 Plan of Selected Areas, 359–381, 446 Osiander, Andreas, 91, 263 Planck, Max Karl Ernst Ludwig, 570 Oude Boteringestraat, 98, 226, 227, 234, 235 planet, 38 Oudemans, Jean Abraham Chretien,´ 36, 37, 62, planetary nebula, 207, 536 78, 79, 97, 100, 102, 187, 189, 233, 286, Plaskett, John Stanley, 530 538 plate constants, 174 Oxford Observatory, 576 Plaut, Lukas, 377, 379, 380, 628 Pleiades, 78, 208, 222, 223, 318, 384, 385, 402, 495, 537, 548 P Plummer, William Edward, 146, 613 Palomar Observatory, 401 Pogson, Norman Robert, 46 Palomar Observatory Sky Survey, 195 Poincare,´ Jules Henri, 352, 366, 404, 569 Pannekoek, Antonie, 137, 204, 446, 581–584, Poisson, Simeon´ Denis, 39–41, 43 592, 597, 625 Polaris, 46, 65 parallactic method, 174, 193, 194, 613, 614 polarization of light, 46 parallactic motion, 295, 316 Polytechnical School Delft, 94, 96, 512 parallax, 138, 139, 300 Pontecoulant,´ Philippe Gustave le Doulcet, 631 secular, 49, 139, 292, 388, 391, 408, 534 Porter, Russell Williams, 322 Solar, 75, 76 Potsdam Astrophysikalisches Observatorium, spectroscopic, 547–549 193, 206, 241, 250, 286, 296, 301, 376, trigonometric, 376, 387, 390, 548 377, 490, 519, 548, 557, 586, 642 Paranal Observatory, 402 Praesepe, 622 Paris Observatory, 119, 158, 184, 185, 187, precession, 64, 74, 291, 540 188, 190, 253, 376 precessional constant, 64, 299, 300 Parkhurst, John Adelbert, 414 prime focus, 490 parsec, 138, 139 prime vertical, 130 Parson, William, 404 Princeton Observatory, 471 Pasadena Star (newspaper), 122, 123, 125 Proctor, Richard Anthony, 48, 231 Passage, de (Cafe-restaurant),´ 423, 425 proper motion, 48, 74, 139, 300 Paul, Erich Robert, viii, 363, 557, 567, 592, parallactic, 295 625, 647–649 reduced, 436 Pearson, Karl, 506, 508, 510–515, 618 Protestant church, 3, 15, 25 Peary, Robert Edwin, 511 Proxima Centauri, 135 Pease, Francis Gladhelm, 468 Ptolemaeus, Claudius, 74 Perdok, Wiepko Gerhardus, 433 Ptolemy, 74 perihelion, 61, 79, 113 Pulkovo Observatory, 62, 185, 187, 190, 216, period-luminosity relation, 372, 590 231, 300, 336, 339, 353, 362, 376, 538 Perrault, Charles, 188 Perrault, Claude, 188 Q Perrier, François, 189 quadrant, 59 Perrine, Charles Dillon, 312 quantum efficiency, 153 Perry, Stephen Joseph, 189 quasar, 333 Perryman, Michael, 155, 384 Quetelet, Lambert Adolphe Jacques, 506 photographic process, 153–154 Quintus Horatius Flaccus, 658 Physiological Laboratory, 98, 171, 172, 226, 233, 418 R Piazzi, Giuseppe, 38 Racine, Jean, 12 Index 695

Radcliffe Observatory, 362, 376, 378 Royal Society of London, 298, 515, 572 Raimond, Jean Jacques, 628 Royal Swedish Academy of Sciences, 631 Ravensperger, Hermann, 90 Royal Swedish Society of Sciences (Uppsala), Rayet, Georges Antoine Pons, 253 631 Rayleigh scattering, 412 RR Lyrae stars, 379, 592 Rayleigh, Lord (John William Strutt), 412 Rueb, Adolf Stephanus, 36 reciprocity failure, 154 Ruijs de Beerenbrouck, Charles Joseph Marie, red giant, 207, 312, 410 584 Reduction of Groningen, 86 Russell, Henry Norris, x, 206, 415, 487, 548, reflection nebula, 402, 537 555 reflex zenith-tube, 236 refraction (atmospheric), 66, 67, 127, 128 S Repsold factory, 77, 129, 135, 199, 226 Sandage, Allan Rex, x, 454, 458, 460, 465, Republic Observatory, 204 468, 491, 547 Republic of the Seven United Netherlands, 86 Saros period, 124 Reunion,´ 79 satellites (moons), 38 Reynolds, John Henry, 211 Saturn, 154 Rhodes. Cecil, 354 Savornin Lohman, Witius Henrik de, 92 Richmond, Myrtle L., 488, 624 Sawerthal, Henry, 178 Riemann, Georg Friedrich Bernhard, 41 Schonfeld,¨ Eduard, 163, 189, 231, 351, 523 right ascension, 63–65, 126 Schaub, Werner, 624 Ristenpart, Frederich Wilhelm, 318 Scheiner, Julius, 250, 286, 615 Ritchey, George Willis, 312, 458 Schiller, see von Schiller Roberts, Isaac, 189, 222, 223 Schilt, Jan, 627 Rondeel, E.J., 371, 372 Schlesinger, Frank, 487, 530 Roosevelt, Franklin Delano, 529 Schmidt, Maarten, 369 Roosevelt, Theodore, 344 Schols, Charles Mathieu, 96 Rossijn, Johannes Theodorus, 29, 636 Schoute, Pieter Hendrik, 433, 434 Rotterdam, 653 Schouten, Willem Johannes Adriaan, 556, 592, Rousseau, Jean-Jacques, 12, 25, 45, 149 623, 626 Rover safety (bicycle), 307, 656 Schwarzschild, Karl, 357, 358, 368, 418, 485, Royal Academy Dublin, 631 487, 490, 530, 541, 548, 554, 556, 563, Royal Academy Edinburgh, 631 568, 570, 642 Royal Astronomical Society, 131, 342, 555, Schwassmann, Friedrich Karl Arnold, 376 607, 630, 631 Schwearzschild, Karl, 568 Gold Medal, 351 Schwieger, Walther, 571 Royal Geographical Society, 256 Seares, Frederick Hanley, 378, 468, 469, 487, Royal Greenwich Observatory, 74, 81, 187, 488, 499, 521, 550–555, 599, 605, 624, 190, 196, 203, 231, 236, 295, 356, 376 625, 645 Royal Military Academy, 94, 96 Searle, Leonard, 565 Royal Natural Sciences Society, see Secchi, Pietro Angelo, 288 Natuurkundig Genootschap (Groningen) secession of 1834, 15 Royal Netherlands Academy of Arts and secular parallax, 48, 139, 292, 388, 391, 408 Sciences (KNAW), 94, 119, 270, 284, Seeberg-Sternwarte, 73 286, 290, 293, 295, 297, 319, 321, 323, Seeliger, see von Seeliger 326, 365, 398, 405, 408, 483, 534, 540, Selected Areas 574, 611, 631, 674 photometric sequences, 378–379 Royal Observatory of Belgium, 506, 576 Shapley, Harlow, 377, 378, 415, 488, 555, 567, Royal Observatory, Cape of Good Hope, 131, 568, 589–592 139, 167, 238, 243, 256, 287, 352, 353, sidereal day, 65 362, 376, 491, 671 sidereal time, 65 Royal Physiographical Society (Lund), 631 Sijmons, Barend, 104 Royal Society, 156, 159, 163, 166–168, 185, Simbad data base, 669 196, 198, 200, 202–204, 631 Simons, Gerrit, 62 696 Index sine functions of higher orders, 119–121 Stieltjes, Thomas Joannes, 69 Sirius, 46, 135, 213, 215, 291 Stockholm Observatory, 552 Sitter, de, see de Sitter Stokes, George Gabriel, 163, 168, 198 Skew Curve Machine, 508, 509 Stone, Ormond, 336 skew frequency curves, 505–516 Strasbourg Observatory, 96 sky brightness Stratingh, Sibrandus, 277 total starlight, 361, 437, 540 Stratonoff, W., 404 Slipher, Vesto Melvin, 485 Stromberg,¨ Gustaf, 552–555 Smid, Etine Imke, 539, 621, 626 Stromgren,¨ Bengt Georg Daniel, 432 Smith, Robert W., 567 Stromgren,¨ Svante Elis, 432, 491, 533, 575, Smithsonian Astrophysical Observator, 468, 576 485 Strutt, John William, 403, 570 Snellius, Willibrord, 59 Strutt, John William (Lord Rayleigh), 412 Snow Telescope (Mount Wilson), 456, 458 Struve, see von Struve Snow, George Washington, 458 Sturm, Charles-François, 25 Society of Arts and Sciences of the Province Südliche Durchmusterung, 74, 156, 163, 285, of Utrecht, 168, 631 523 Solar Apex, 139, 290, 299, 301, 316, 321, 323, Suermondt, Eleonora, 258 324, 389, 434, 534, 542 Sullivan, Woodriff Turner III, 380 Solar constant, 485 supergiant, 209 Solar eclipse, 124, 540 superluminal velocity, 314 Solar parallax, 75, 76 supernova, 209, 401 Solar System, 37, 38 synodic month, 124 Solar Towers (Mount Wilson), 456, 458 Sonnenborgh, 36 Southern Cross, 153, 354 T special relativity, 312 Tammes, Jantina, 507, 513 Spectral types, 288 Tashkent Observatory, 404 spectroscopic binary, 387 Taurus (constellation), 384 spectroscopic parallax, 547 Technical University of Delft, 502 speed of light, 67, 312 ten Bruggen Cate, Gerrit Hendrik, 557, 623, Spencer Jones, Harald, 256 626 spiral galaxy, 211, 404 ten Bruggencate, Paul, 557 St. John, Charles Edward, 599, 607, 653 Tennant, James Francis, 189 Staatkundig Gereformeerde Partij, 3 Tennyson, Alfred, 497 star Teyler Foundation, 168 classification, 288 Teyler van der Hulst, Pieter, 168 evolution, 76, 536 Thackeray, Andrew David, 378 formation, 206 Thackeray, William Grasett, 357 magnitude, 46 Thijsse, Jacobus Pieter, 654 mass, 76, 207 Thomson, Joseph John, 403, 525 spectroscopy, 289 Thomson, William (Lord Kelvin), 270 Star Streams, 315–349, 352–359, 434, 486, tides, 501–504 494, 523, 533, 535, 537, 542, 568, 614 Tienemann, Johannes, 283 Statistical astronomy, Fundamental Equation Tietjes, Friedrich, 62 of, 332 Tisserand, François Felix,´ 192 Stebbins, Joel, 378 Towsend, Euphemia Clementina, 32 Stein, Johannes Wilhelmus Jacobus Antonius, Transvaal Republic, 274 323, 436, 617 Treaty of the Metre, 190 Stellar Populations, 209, 244 tree rings, 122–126, 147 Stellar Statistics, Fundamental Equation of, Trepied,´ Charles, 193 332 triangulation, 60 Sternwarte Gottingen,¨ 357, 490, 642 true anomaly, 112, 113 Sternwarte Karlsruhe, 300 Trumpler, Robert Julius, 417, 567, 568 Index 697

Turner, Herbert Hall, 139, 184, 191, 327, 336, van der Heijden, Petra, ix, 249, 270, 365, 366, 338, 555, 576, 587 587 Twain, Mark, 153, 354 van der Kallen, Hendrikus Frederikus Two-body problem, 113 (Havank), 263 van der Kruit, Pieter Corijnus, ix, xi, xii, 213, U 215, 317, 437, 560, 561, 565, 597, 626, Undina (minor planet), 37 647 Union of Utrecht, 86 van der Kruit-Arends, Cornelia, v, xii, xiii universal instrument, 77, 129 van der Waals, Johannes Diderik, 34 University of Amsterdam, 27 van der Wijck, Bernhard Hendrik Cornelis Karel, 85, 98, 101 University of Capetown, 630 van Dijk, Isaac, 466 University of Edinburgh, 630 van Gent, Hendrik, 628 University of Franeker, 27 van Gorkom, Wilhelmina Henriette, 148, 306, University of Groningen, 27, 86 609, 610 tercentennial, 517 van Heiden Reinestein, Louis (Graaf), 92 University of Harderwijk, 27 van Hennekeler, Andreas, 68 University of Lausanne, 219 van Herk, Gijsbert, 628 Urania Observatory, 642 van Hulsteijn, Johanna Josephine, 32, 109 Uranus, 38, 211 van Lokhorst, Jacobus, 220, 225 Ursa Major, 46 van Maanen, Adriaan, 98, 434, 490, 492, 493, US Naval Observatory, 74, 80, 270 525, 538, 543, 553, 591, 599, 625, 626 Utrecht Observatory, 36, 100, 170, 490 van Rappard, Anthony Gerhard Alexander Utrecht University, 27 (Ridder), 62 Utrechts Studenten Corps, 31 van Rees, Richard, 29, 39, 636 Utrechtse Studenten Almanak, 39 van Rhijn Luminisity Function, 379 Uylenbroek, Pieter, 61 van Rhijn, Pieter Johannes, 14, 170, 204, 302, 332, 361, 369, 372, 376, 380, 413–416, V 420, 430, 488, 490, 493, 540, 551, 554, Valentiner, Karl Wilhelm, 68, 79, 96, 117, 137, 556–561, 570, 577, 579, 582, 592, 597, 404 602, 621–627, 636 van Ankum, Hendrik Jan, 93 van Schaffelaar, Jan, 4 van Anrooij, Peter Gijsbert, 305, 427, 608 van Swinden, Jean Henri, 29 van Bell, Frederik Willem Bernard, 98 van Swinderen, Theodorus, 276, 279 van Berkel, Klaas, ix, x, xv, xvii, 30, 31, 102, van ’t Hoff, Jacobus Henricus, 34, 570 107, 109, 493, 609, 626, 647, 667 van Uven, Marie Johan, 512, 622 van Calker, Friedrich Julius Peter, 88 van Wageningen, Jacobus, 577 van de Kamp, Peter, 627 van W¨urttemberg, Sophia Frederika Mathilde, van de Linde, Jan Cornelis, 539, 627 218 van de Sande Bakhuyzen, Ernst Frederik, 69, variable star, 76 70, 73, 77, 79, 138, 162, 305, 447, 448, Vatican Observatory, 288, 323, 397 491, 539, 540, 581, 583, 612 Vega, 139, 291, 327 van de Sande Bakhuyzen, Hendricus Gerardus, velocity dispersion–age relation, 532, 552 65, 68–81, 93, 97, 100, 102, 104, 118, Venus, 76, 79, 131, 158 121, 129, 140, 143, 144, 162, 187, 189, vernal equinox, 65 192, 193, 197, 225, 232, 248, 252, 258, Versailles, Peace of, 572 286, 305, 309, 320, 323, 338, 355, 357, Vertex of Star Streams, 341 371, 386, 405, 406, 444, 445, 447, 448, Verweij, Albert, 111 469, 539, 562, 575, 581, 582, 588, 606, Veth, Jan Pieter, 420, 576–580 612, 613, 652 Vindicat Atque Polit, 432 van de Snepscheut, Johannes Lambertus Voute, ˆ Joan George Erardus Gijsbertus, 491 Adriana, 27 Vogel, Hermann Carl, 193, 296 van den Bos, Willem Hendrik, 628 Vollgraf, Carl, 643 van den Broeke, Henrik, 108 Voltaire (Franc¸ois-Marie Arouet), 233 698 Index von Auwers, Arthur Julius Georg Friedrich, Weigel, Erhard, 638 570 Weldon, Walter Frank Raphael, 506, 510 von Auwers, Georg Friedrich Julius Arthur, Wesselink, Adriaan Jan, 628 74, 139, 187, 190, 192, 197, 200–202, Wheatstone, Charles, 40 295, 299, 300, 616 Whirlpool galaxy, 404–406, 536 von Beethoven, Ludwig, 608 white dwarf, 207, 312 von Goethe, Johann Wolfgang, 12, 25, 652 White House, 344 von Helmholtz, Hermann Ludwig Ferdinand, Whitehead, Alfred North, 501 219, 270 Wilhelmina, Queen of the Netherlands, 218, von Humboldt, Friedrich Wilhelm Heinrich 226 Alexander, 200 Wille, Sara, 109 von Leibniz, Gottfried Wilhelm, 638 Willem III, King of the Netherlands, 97, 218, von Littrow, Karl Ludwig, 140 226 von Oppolzer, Theodor, 115, 117 William Herschel Telescope, 633 von Schiller, Johann Christoph Friedrich, 12, Wilson, Thomas Woodrow, 572, 576 33 Wisse, Anna, 304 von Seeliger, Hugo Hans (Ritter), 96, 231, 415, Wolf, Charles Joseph Etienne,´ 253 418, 556, 557, 561–563, 567, 570, 576, Wolf, Maximilian Franz Joseph Cornelius, 632 586 Wolf-Rayet star, 253 von Seeliger, Hugo Hans, Ritter, 363, 479 Woltjer, Lodewijk, 568 von Steinheil, Carl August, 46 Wood, De Volson, 383 von Struve, Friedrich Georg Wilhelm, 139, Woodward, Robert Simpson, 463, 467 216, 231, 403, 439, 498 von Struve, Otto Wilhelm, 185, 187, 190, 192, Y 197, 202, 216, 339, 432 Yale Observatory, 135, 376, 471 von Tschirnhaus, Ehrenfriend Walter, 638 Yerkes Actinometry, 414 von Wolff, Christian, 638 Yerkes Observatory, 48, 312, 336, 344, 362, Vulcanus, 78 365, 376, 454, 458, 471, 486, 491, 531, 572 W Yntema, Lambertus, 361, 434, 437–443, 538, W Virginis stars, 592 540, 541, 619, 626 Wagner, Wilhelm Richard, 387 Young, Charles Augustus, 327 Walloon Reformed Church, 107 Washburn Observatory, 146, 300, 325, 336, Z 362 Zeeman, Pieter, 483 Washington University, St. Louis, 333, 337, zenith distance, 127 344 Zernike campus, 634 Watt, James, 131 Zernike, Frederik (Frits), 308, 372, 374, 522, weather, 122–126 557, 582 Weersma, Herman Albertus, 372, 386, 388, zodiacal light, 438, 541 434, 450, 535, 538, 556, 582, 618–621, Zollner¨ photometer, 46–48, 73, 258, 287, 441 623, 626 Zollner,¨ Johann Karl Friedrich, 46